Maximum Fish Population

herring_fish

Crazy Designer
I have a 180 gallon tank that I am restarting in an upgrade. I have been reefing for 25 plus years and have always known about the old inches of fish at maturity, per gallon rules.

Now I am building a system that will have more water outside the Display Tank than inside. I have never had a problem keeping N and P at zero, no matter what I do to the tank. And that is without a sump and all. Now with so much external water cycling through the tank I don't think that I will have a problem with nutrients. In addition to powdered and flake food, I plan to produce an abundance of live food in the DT. One concern that I have is a lack of available hiding places in a display tank of limited size. I have built some fish motels but I don't think there will be enough.

Now I am wondering about those old rules as they would apply to this situation.

In the wild, I see extremely high concentrations of fish where food is plentiful. I am sure that is for comparatively short periods of time but there are mix species mingling in very close proximity.

Now if I had that in my tank, it would look like chaos to say nothing of the bio-load. On the other hand, if I have a few schools of various fish, things could quickly get out of hand and exceed any of those rules of thumb.
For that reason, I would like to look at the limiting factors that go beyond nutrients in the water column and available food.

What other factors do I need to consider and what warning signs would I look for as I slowly add fish?
 
It's really more about what fish you want specifically that will dictate how many and what other fish can be kept in the tank
 
Have to agree with the above. In an old 260 I have filled with softies I kept roughly 65 fish, 50 or more being anthias. I ran a large Deltec skimmer, did weekly water changes and ran a good size refugium. In my case it seemed to be fine. I fed super heavy due to the anthias in the display and with all softies everything grew like crazy. Can large fish loads be done? Sure but IMO you have to choose the fish carefully and stay up on husbantry.
 
Wow. Awesome tank!

I take it that tank is no longer up and running?

Sadly no. Came down due to a relocation. Has always been my favorite with not only fish species but also location in the house. Was always a great conversation piece being right off the kitchen.
 
This. And there is no inches per gallon rule.

I've found out that most rules don't hold true...

i.e.
- Add all tangs at the same time to reduce aggression.
- Tangs are mostly aggressive to only the same body types.

Had those both proven wrong in our tank.

More comes down to each fish' personality, social structure in the tank, how they act as they mature and grow, etc...

Our YB Blue Tang was a punching bag when he was 2-3". Now at 5-6" he's a beast and will even chase around Triggers.
 
There has been a lot of good stuff.


Thank you


I have always had a low fish count so I never read much about it and didn’t observe much either. I really don’t know anything about fish behavior so this is helpful.


Please keep it coming.
 
I am a strong believer in high fish populations leads to less aggression.

Want to have a pretty heavily stocked tank before I add my final 3-4 tangs.

Will have a crazy amount of money wrapped up in fish, so I don't want to lose one or more to aggression.
 
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