IMO How to set up a tank to stay healthy and immune

Paul B

Premium Member
Remember, I am an electrician, (a really good electrician) and I am not a researcher or scientist, I also don't have as many degrees as a thermometer. I did not even go to college, there was that war thing and besides that I hate school and would rather learn what I want to learn when I want to learn it even though I know now you could take a course in Beyonce. That will get you far in life. :cool:

Some history: I learned most of what I know about fish by spending about 400 hours with them underwater in oceans all over the place. Not tourist diving when all the divers in a resort follow an instructor around a reef that 17,000 divers "explored" before you. I have my own boat and equipment and when I went to the tropics, I hired a local guide to show me what I asked him to show me and thats how I learned. Lay on the bottom until you run out of air. Much of my dives were at night in New York hunting for lobsters in close to zero visibility.

Enough about me. If you don't believe fish can become immune, like they are in the sea, go and watch Oprah or "The View" :oops:

To know about fish you have to know how they think. You will learn that by observing them in the sea.

The first thing we see is that fish don't like us and they are afraid of us, yes even if you look like Angelina Jolie. As soon as a diver gets about 7' from a coral head, all the fish will dive in and get completely out of sight. Thats what they want to do,,,ALL fish. No fish in the sea is going to stay there while you get close to them.

But in a tank, they are stuck, they can't get away. They can't get 7 feet from you and in a majority of tanks, they can't even hide from you. This one thing is a huge problem in keeping fish in a Home Tank. Public aquariums are different and in those tanks, the fish are at ease.

So thats one problem but we can correct that as much as possible. Another big problem is that all bony fish have a "lateral Line" that I have never heard one person mention in 60+ years of doing this and it is the single most important thing on a fish. It is more important than their sight, smell and hearing. Fish can get along fine without those senses but would die in minutes without their lateral line.

You can clearly see it on this Copperband. It's the line of scales that start behind the eye and arc up around near the top of the fish and goes to it's tail.

Most of us don't have this line but all fish do and it is the most important part of a fish and has an enormous job to do for the fish.
That line of fluid filled tubes is the radar of the fish. It uses it to "feel" it's surroundings. Robert Straughn The Father of Salt Water Fish Keeping called it "Remote Feel". We never speak of it but instead worry about flake food or rice Crispies. It is as crucial to a fish as our skin is.

That is why you can never catch a fish with a net unless you cheat and corner the fish against something. Try to catch a fish with a net in the open sea by chasing it with a net. Even though the fish can't see the net, it knows exactly where the net is. Ever wonder why a fish never crashes into the glass in a tank? Not even in pitch darkness? The lateral line. And remember, the fish can't see the glass just like we don't see it when looking right through it.

That line is crucial to a fish but a big hinderance in a tank. Why you might say? Because the fish can "feel" the glass and being he can't see it, it drives them nuts.
(IMO that is how HLLE comes about and it always affects the lateral line first)

The nerves in the lateral line constantly bombard the fish with signals that in the sea would cause it to flee from an unknown threat, but they can't in a tank.
The fish can also feel the water surface and substrate and know they should be much deeper because none of the fish we keep live in 16" of water so they constantly want to get into safer, deeper water, but in a tank, they can't. It's like if we were in a see through cell where we can't see the bars but we can see predators walking by all the time. It would be scary. (Unless of course we see Ms Jolie)

These are a few things that cause stress in fish. I will continue below.
Nice Paul. I’m with you on not diving the cattle boats. My family always preferred to hire a private boat in the Caribbean.
How does stress affect fish? We get stressed if we lose our lip ring or get a pimple on the tip of our nose. But these are not life threatening events. (well, the pimple may be. I once totally shaved off one of my eyebrows because I was trimming them and forgot to put that comb thing on the shaver. I didn't go out for a year) :oops:

We have something in our DNA, our genes called Telomeres. They are a protective cap on the end of our chromosomes that keep the thing from unraveling just like an aglet. (the thing on the end of shoe laces) As us (or fish) age that telomere gets shorter and shorter until it is no longer there and can no longer protect the chromosome. That is when we die of old age and why we don't live forever. That is what controls the lifespan of every living thing.

But guess what? Stress makes us release cortisol the stress hormone. Cortisol does many things, one giving us strength to get away from danger. It can dissolve our bones to give our muscles quick energy. It does a lot of things which are good and our level of cortisol varies through the day. This is normal and good. It's not good when we are constantly stressed like I said above as the cortisol will keep building up and being the fish can't get away it gets to dangerous levels.

A couple of things excess Cortisol does is weaken our bones, bring viruses out of remission (Due to a suppressed immune system "AND" it prematurely shortens our or the fishes Telomeres which as we found out, controls our life span.

So stress also shortens our lifespan through the excess of cortisol due to stress. Now no one knows exactly how long a fish is supposed to live but if it is supposed to live 8 years and the cortisol shortens it's lifespan by 25%. Now that fish may have a lifespan of 6 years.
(About, work with me here)

I didn't make this stuff up in a drunken stupor. I think of other things in a drunken stupor. Being my wife has MS we go to a lot of talks by neurologists and that is where I get this telomere stuff. Fish also have telemeres and make cortisol so anything where the fish is stressed it will make cortisol thus "REDUCING IT'S LIFESPAN". Isn't that special.

So now we can talk about how we can set up a tank to aleve this problem in a tank. But we are invited out to dinner now so I will get back to this......Unless I have to much tequila and tonic my favorite drink. :giggle:
I will get to setting up the tank eventually but I think first we need to know about the immune system of fish.

Our skin is composed of dead cells on the outside to make us water proof, to an extent. A fishes skin is living all the way through and is semi porous "almost" like our reverse osmosis filters but a fishes skin can move certain hormones and salts through.

All, or most fish have slime that covers their entire body including in their gills and down their throat. The slime is not to make the fish slippery so it can swim faster or squeeze into tight places. Their slime is the fishes first defense against disease. First off it is water based so it constantly sloughs off as the fish swims forcing the fish to constantly renew it. As the slime is washed off, many parasites go with it but that is not the main defense.

The slime, in a "healthy" fish that has immunity will be full of antiparasitic chemicals. The slime is oozed out in many places and a fish wouldn't live very long at all without it. But a fish that lost it's immune system by not being in contact with pathogens for a period of time, differing with different species of fish, their slime will still be produced, but it will be lacking the antiparasitic properties. If you don't use it you lose it.

Thats why we get booster shots.

A fish uses the calories in it's food for 3 main things. One is to keep alive and have their organs working properly and growth. Actually that probably uses the least amount of calories.

Then a fish uses calories for reproduction and a female fish can produce millions of eggs depending on the fish. Healthy Female fish constantly produce eggs weather there is a male there or not. Eggs are mostly oil so they take up an enormous amount of calories to produce.
Female Humans also produce eggs constantly up to a certain age.

The last thing a fish uses calories for is immunity. It takes a lot of calories to produce that slime and make antibodies to all those things a fish eats including parasites, bacteria, viruses and funguses.
The pathogens in a fish are processed mostly in it's kidney and it's kidney is huge, not like ours then in other organs it determines what antibodies to make and put into their slime.


We are almost there. Now we are talking about gut bacteria.

Something almost always overlooked as Lateral lines it is almost never posted about but it is gut bacteria, good and bad that controls our immunity (Along with fish) and is probably the reason when we medicate fish with almost anything for example a parasite. The fish contracts something else. We all know this and can look at any disease forum to prove it.​


The Gut Microbiome and Health​

Understand the gut microbiome and its role in fighting off infections such as recurrent C. diff infection.

What is the gut microbiome?​

Your gut is home to trillions of different, living microbes all contributing to your health and wellness. This is called your gut microbiome. Together, these microbes—including both good and bad bacteria—can do many things, including help protect against infections.1-3
Healthy Gut Microbiome

What does a healthy gut microbiome look like?​

A healthy gut microbiome is a complex mix of many different bacteria, made up mostly of 2 categories known as Bacteroidetes and Firmicutes, working together in balance to maintain gut health by1-3:
  • Regulating immune function4,5
  • Protecting against inflammation6-11
When the volume and mix of bacteria are compromised, the microbiome is disrupted.2,12
Disrupted Gut Microbiome

What happens when a healthy gut is disrupted?​

If this important mixture of bacteria (including Bacteroidetes and Firmicutes) is disrupted, it can place you at risk for infection. One of the infections is called C. difficile (or C. diff).12

C. diff infection and its recurrence​

C. diff is a bacteria that can cause an infection in the gut. Symptoms can range from diarrhea to life-threatening damage to the colon.12 Sometimes, a C. diff infection can come back more than once. This is called a recurrence.2,12 If left untreated, it too can cause severe illness, and even death.12
Microbiome disruption increases the risk of C. diff infection recurrence.12,13
  • Antibiotics treat C. diff infection but can also be a leading cause of C. diff recurrence12,13
  • Probiotics are recommended only to keep a balanced gut healthy and are not recommended to treat or prevent C. diff.
    Some believe probiotics can negatively affect gut health after antibiotics14-16

End quote​

Gut bacteria does not magically appear in the fishes gut. Yes, they do have bacteria in their gut or they could not be able to digest food, but if you medicate or use long quarantine that gut microbiome may be disrupted leaving the fish open to all sorts of diseases.
Also if we only feed foods from a LFS or (God Forbid) only dry or freeze dried foods our fish will not have the correct bacteria to keep it healthy. Probiotics are not gut bacteria. The correct gut bacteria only comes from one place, the guts of other animals.

Remember in the sea all fish eat fresh, whole fish. Even tangs which eat seaweed because on that seaweed are all sorts of tiny creatures and if you see a tang in the sea, they don't bite off the seaweed, they suck it off the rocks because it is usually so short we can't see it. Also tangs will eat anything including small fish and shrimps. I never feed my tangs nori or greens and after ten years they still look perfect.

Gut Microbiome and Overall Health:

  • The gut microbiome refers to the microbes and their genetic material found in our gastrointestinal tract. These microbes include bacteria, fungi, yeast, and viruses.
  • Approximately 100 trillion microbes reside inside the human body, with many of them residing in our gut.
  • As we ingest food, gastric acid in the stomach destroys pathogens, but some microbes escape and move down to the intestinal tract.
  • Factors like diet, infections, and certain medications can affect the balance of the gut microbiome.
  • A healthy gut microbiome plays a crucial role in digestion, metabolism, and inflammation.
  • It also helps synthesize essential vitamins, enzymes, and hormones needed by our body.
  • Stress can damage the gut microbiome, exacerbating mental health issues.
  • End Quote
I am not going to post all the ways gut bacteria controls immunity but you can read about some of it here:

OK so how do we get the right gut bacteria into our fish? Very easy. All animals harbor gut bacteria so all we have to do is feed "Whole, small, animals" . Things like live worms, fresh or freshly frozen shellfish like clams, mussels, snails or oysters. I use most of those things but you don't have to feed those things every day. Once or twice a week should be fine.
Great article! I had an experience recently with a powder blue tang here in my office that houses a purple tang, sub adult blue face angel, spotted mandarin and a cleaner shrimp. For months the powder blue was looking great until one day it started as white spots, then white things hanging off the fish along with white spots. The BF and purple showed no issues and this kept up for a month +. The PB is the most aggressive eater and that continues every day. I have to watch when adding frozen so I don’t hit him in the head with a spoon of food. Added Boyds Vitachem to the food and aquarium and in a week it was all clear and has remained all clear. I am guessing something was missing from its diet the vitamins fixed it? My fish are spoiled Monday thru Friday I am here in my office 11 hours each day with frozen(LRS and Spirulina Brine) being fed four times a day and pellets four times. On weekends my pellet feeder goes off four times daily with natural grazing on rocks and the back glass.
Now we can discuss how to set up a tank to be immune. As I said in the beginning, if you don't believe fish can become immune, go out for a walk, maybe jog a little and get some fresh air. But since my fish seem to be 100% immune from communicable diseases I will my discuss my method.

This isn't necessarily the only method but it has worked for me since Nixon was President, he was after Lincoln.

I feel the vast majority of tanks, although beautiful are not set up correctly for the fish. If we want to set up the tank just for us, we are making a mistake because we need to think like a fish. As I do this I keep opening and closing my mouth and moving my ears. I said initially we have to be able to read the minds of the fish, and after 50+ years of diving, I think I know what fish want.

They want mostly to be left alone and not see any predators. We are all predators as it was us who were responsible for the collection of our fish so they don't like us.
They don't like anything bigger than they are and neither do I. If I see a guy 6'8" with his face and every part of his muscular body tattooed and he is snarling and carrying a crowbar, I will be running...Fast

So fish don't want to see us. They want to be able to do what they do in the sea and that is get into a tight hole or cave so they can get completely out of sight. We may not like that but we want to set up the tank to be immune and as we said, stress shortens the lifespan, brings viruses and other diseases out of remission, dissolves the bones and does an entire host of other nasty things so we want to reduce stress as much as possible and fish not being able to hide is a big stressor. A white PVC elbow does not cut it and fish hate anything stark white or smooth as a matter of fact they hate anything you can buy from Home Depot except bricks which I will discuss later.

When I built my aquascape I developed a system where almost all my rock is positioned up above my gravel. This creates tunnels completely through the reef structure where the fish can traverse the entire tank and I can't see them. Bad for me but good for my fish.

I once had a Brutlyd or cusk eel for 18 years and almost never saw him. He was very healthy and is the type of fish that hides. If we buy a fish that is designed to hide, it wants to hide and needs to hide or get sick.

I also have a couple of gecko gobies that I never saw since I added them. I may get a glimpse of a tail if I shoot food near their cave in the back, but thats the type of fish they are. They may live forever like that so if you want to see your fish, don't buy cusk eels or gecko gobies.

We can try but we will not be able to change the natural behaviour of our fish and we need to catere to their likes, not ours.

I built much of my rock by cementing smaller rocks together using regular cement of mortar so they are big allowing me to raise them over the gravel by utilizing very few supports.

Those large rocks are only supported on the ends so they span over 2' and are just over the substrate allowing the fish to access the many holes and caves throughout the tank.

This is a small support made out of PVC pipe and cement and supports my reef in a few places.

I will get back to this
I just got back from my morning walk, Thank God summer is coming. Anyway getting back to the tank. We discussed how to aquascape to keep the fish as stressful as we can.

This is another home made rock. It is bent PVC pipe with a cement covering.

This is a coral reef in Bora Bora. I took this probably 20 years ago.. You can make out a moorish Idol on the bottom center. It is hard to see but the bottom is nothing but passages through the rock and every fish will dive in when you, or those sharks get close. They will not get scratched and they will all fit in because of their lateral line.

This was my tank just when I moved everything here from my old house "before" I put the corals back in. Everything was in vats for the move.
The aquascape is nothing but holes and passageways through the entire 6' tank so the fish can traverse anywhere they want without being seen.

It looks more like this here. I think this was a year or two ago.

So beside the aquascape to reduce stress we need bacteria on those rocks. Bacteria are more important than anything else you can add to the tank. We can get the correct bacteria from live rock but remember when we buy anything from a store that rock may have been there for a year or two so the compliment of bacteria on that rock may be just the same bacteria as the store owner has in his tanks. Of course it could have been in the sea last week. We just don't know but it's the best we have.

I feel if you want to set up a tank with 100% dry rock and ASW, do something else. Get a different hobby, perhaps hang gliding or bungee jumping which would be much easier than trying to start a reef tank that way. Yes, it can be done and was done many times but I am sure most if not all of them had problems.

Such a tank has none of the correct bacteria. We are not talking about gut bacteria here just normal bacteria that will process ammonia which the fish excrete, nitrates which also comes from waste products and phosphate. Those things will build up in a tank without sufficient bacteria causing all sorts of problems forcing many of us to go on the disease forum thinking the fish are sick. They are sick, but not from disease, from unwanted pollutants.

If we put a fish in a tank with ASW and dry rock with nothing else, it will die in a short time due to ammonia poisoning. This is very common and the fish usually dies with his mouth wide open and his gills flared out. Fish have little tolerance to ammonia but the correct bacteria will get out the ammonia in no time and any tank with a little age on it will not have a problem.

This is one reason we see on disease forums a tank full of dying fish with no likely disease problems. It's to new of a tank to have all that life in it and not enough bacteria to process it.

Just 2 days ago I had to go to a wake. My friends son came up to me and said he started a reef tank. Right away I cringed because I knew what was coming next. I asked: What do you have in the tank? He said urchins, crabs, anemone crabs a "bunch" of damsels and a couple of small tangs. I asked when did you set up the tank? 6 weeks ago. I hope he lost my number because those animals are going to die.

Those fish will get sick and he will add all sorts of"treatments" that his LFS will gladly sell him. In a year, he will sell everything and get out of the hobby and get a job in Home Depot loading toilet bowls into mini vans.

His tank is way to new to add almost anything, especially tangs and anemone crabs which are filter feeders.
It takes time to build up enough and the correct type of bacteria for almost anything to live correctly and bacteria in a bottle (whatever that is) won't help.

We need a variety of bacteria, viruses and funguses to thrive and eventually get along so the tank runs on auto pilot. That will take a couple of years and not weeks.

My wife is up, I need to make breakfast so I will have to get back to this
To me a tank does not start to achieve stability until you see growth on the rocks. No, we don't want it covering our corals but some growth is normal and natural. If your rock is still bare rock, don't put in anything that you don't want to lose and especially creatures that live on copepods or algae. It just isn't there and that mandarin you bought last week is going to die no matter how much medication you dose him with because he is not sick, just hungry.

These guys should live about 10 years with no extra feeding from us. But we can't clean the tank to death or use any medications.

You also can't feed a mandarin long term by buying pods (sorry people who sell pods) I am not sure if those pods they sell reproduce in a tank but I assume if they do, they would be fine. But a tank needs a large breeding population of pods to keep even one mandarin thriving.

Even pods won't live on bare, white rock so the tank needs some time to build up some growth before most fish should be added.
This little pregnant bleeny eats whatever she finds crawling around on that rock and she has enough to eat on that one rock that she hardly has to move.

This is her main squeeze, notice the growth on the rocks. Many people would get out the power washer, but this is actually very healthy

I took this in the Florida Keys, These are Mangrove roots which is a breeding ground for many fish in Florida. Notice the growth, that is food to most fish and is needed and not a bad thing.

So we know how to aquascape to kind of make the fish as happy as possible but we have to feed them. I am not a big proponent of any dry foods for a couple of reasons. Dry foods for the most part are baked, especially flakes. Baking destroys many vitamins and all the gut bacteria so they have to add it later. Like white bread, did you ever notice it has all sorts of added vitamins and minerals. The manufacturers of white bread don't really care if their product is healthy, but if they didn't add vitamins and minerals they couldn't call it food because there is no nutrition in white bread.

Manufactured dry foods can't have any bacteria or they would rot. All of them that I am aware of have preservatives. I am holding a container of manufactured food from a very reputable manufacturer and it states it is natural with vitamins and minerals added.

Real food has everything in it that fish need and the ingredients should be one word, something like clam, worms, mysis or something like that. The can of pellets I am holding (and it's hard to type and hold this container) has ingredients listed and it would take up an entire page to list them all. I counted them and there are 55 ingredients. Some of them are artificial colors (which are for us, not the fish) and 4 or 5 are preservatives.

If we want our fish immune we can't use this stuff because although it will keep fish alive, it will do nothing for their immunity so if you are feeding dry foods, forget what you read on this thread and go out and plant your tomatoes because your fish will not become immune and you will have to spend time on disease forums.

As I said, fish need gut bacteria and you will only get that from "some" commercial frozen foods that are "NOT" irradiated to kill "harmful" parasites. We can think of parasites as a good thing "BUT NOT RIGHT AWAY". First we have to make sure our fish are immune.

My staple food is LRS food and Rods food along with frozen salt water mysis. But to make sure they are getting fresh food with living gut bacteria I add a few times a week live blackworms, whiteworms, clams, mussels, oysters or earthworms. These fresh, live foods are the absolute best but not always for sale in a LFS.

Not all these foods, just one will supply our fish with a shot of healthy gut bacteria and fish need good and bad gut bacteria to become immune. Pro biotics are good bacteria which is good for health but the fish also need bad bacteria like they eat in the sea with every meal. They also need parasites if you want them to be immune but you don't have to add them. If you didn't quarantine or medicate your new fish they already have parasites and those parasites are a non issue for healthy, immune fish.

Time to eat...Me, not the fish.
Wow! Thank you - what a great explanation! Where do you source your fresh food from? How soon after you have cycled and added fish before you start adding the live food, or do you wait a while? Thanks
Nancy, I got back 20 minutes ago from my morning walk. It is raining so I brought a tweezer and plastic bad to collect earthworms. I have 3 Red Waspfish and thats their favorite food and shun most other foods so I collect for them. My 20 worms will last a month. Besides that I raise whiteworms in soil. They live on bread and some yogurt.

I also feed freshly frozen clams. I cycled my tank in 1971 but I started feeding live blackworms as soon as I put fish in.

“Gut microbiota can affect fish physiology, development, life span, immunity, and barriers against pathogens (Burns et al., 2016; Nie et al., 2017; Smith et al., 2017; Yan et al., 2016). Therefore, the gut microbiota plays an indispensable role in fish fitness. Several recent reviews have centered on the diversity and functions of bacterial communities in healthy fish (de Bruijn et al., 2017), as well as on the external factors that affect fish gut microbiota (Wang et al., 2017) and interactions between gut microbiota and innate immunity in fish (Gómez & Balcázar, 2008; Nie et al., 2017). However, most previous studies have focused on factors that govern healthy gut microbiota, such as diet, rearing conditions, and fish genotype (Schmidt et al., 2015; Sullam et al., 2012; Yan et al., 2016). In contrast, few studies have reported on the interplay among gut microbiota, fish immunity, and disease (Nie et al., 2017). In this commentary, we summarize current knowledge on the associations between fish immunity, gut microbiota, and invading intestinal pathogens. We also highlight recent progress in uncovering the ecological processes of fish diseases”
Antibiotics are probably the worst thing we could add to a fish tank unless we have one sick fish and it is in a hospital tank. Even at that, unless I was sure the fish was going to die, I would not use an antibiotic because as I said our tanks run on bacteria and if we kill the bacteria, we will also kill the fish.

Maybe not right away but it will take quite a while for that fish to recover from the antibiotic if it ever does.
Copper is another one most of us have used. I haven't really used it in decades and that was only on an almost dead fish I got for free. If we keep our fish immune there is never any need for medications as the fishes immune system is perfectly capable of keeping disease organisms from affecting our fish.

Copper kills bacteria along with parasites, but it may not be strong enough to kill all the gut bacteria, but it will disrupt it and may kill certain bacteria strains that may make conditions worse.
Copper is also a poison to the fish so it will definitely cause stress and stress causes diseases or at least allow the fish to get sick due to a suppression of their immune system.

It's all about lowering stress mostly through aqauascaping but also through food with it's associated gut bacteria.

I also think a big problem in tanks is the use of chemicals like "Kick Ich" or "Red Slime Remover" to eliminate cyano or "Vibrant". I feel those things have no place in a healthy tank that we are striving to get immune.

The process of fish being immune is all due to the presence of pathogens such as parasites living along with the fish in our tank just as they do in all oceans. If we are determined to kill or eliminate all parasites, we will never achieve immunity. It just can't happen because the fish, and us depend on regular contact with pathogens to become and keep immunity from them. Thats why we get booster shots as our immunity will also wane in time if we don't keep it up.

Paul. All I have to say is WOW! Great work on putting this together for us - so what I'm getting from this is that we are definitely very close to fish, in the sense that our gut biomes work very similar 😀
Yes it seems it does. I did a lot of research on this as I am friends with a couple of neurologists, and I learn what I can about Human physiology then I figure out how it relates to fish. This is very simple but most of us are more worried about seeing a spot than trying to keep the fish healthy in the first place and you do that by thinking like a fish. :rolleyes:
WE have to get away from this idea that dirt is bad for fish. We Humans evolved to eat a lot of dirt in our lives, most Neanderthals didn't have that little push thing next to their Delta sink faucet filled with that nice smelling baby blue Anti- Bacterial soap with the Supermodel or Clownfish on the label.

They used to kill a 5 thousand pound Wolly Mammoth by standing behind a door and tripping him as they lumbered by. Then Mr. Ally Oop Neanderthal would take out his pen knife and carve out a quarter pound piece of meat for a hamburger, if he was married he may cut out another piece for his main squeeze, then they may rinse it off in the same puddle their dog sleeps in and scrape off the 15" Mammoth hair with their teeth before eating it whole. The rest of the Mammoth they gave to the dog or put it in the recycle bin.

Remember Neanderthals walked around for about 400,000 years while we have only been here since they invented Malls so they were pretty successful in spite of all the dirt and Wolly Mammoth hair they ate. Dirt may be the secret to keeping us and reef tanks healthy even though I realize most people today feel dirt is bad, but thats because of advertising and probably lawyers. (I blame lawyers for almost everything)

Fish in the sea eat a lot of dirt and fish poop. Fish poop is mostly gut bacteria so fish know what they are doing and as long as we leave them alone and don't medicate them or treat them like our domesticated designer lap dog they will be fine. We make them sick, no one else. Besides fish don't really have a tongue so may be can't tell the difference between poop and a T Bone steak.