in-breeding in fish and other aquatic critters

[meredith1985]

So I'm wondering what you guys' thought are on this subject. I know that inbreeding in most any creature can create birth defects and imune system problems. Remember when 101 dalmations came out? And all the breeders started inbreeding their dalmations to keep up with the demand for them? Now most of the dalmations you run into have anger issues, immune system problems, hearing issues, sight problems and are just plain dumb. I lucked out with my dalmation because his mother was bread with a german short hair pointer (he's smart).

But the point is.... if we are trying to breed our fish to keep us from going to the ocean for them, wouldn't we want to supply the best and healthiest fish we could? You can feed them the best stuff and keep your water pristein but in the end if you inbreed your fish could you be short-changing them from the get-go? I know a guy on another forum that has two clownfish (brother and sister) and each are missing the opposite eye. He got them from a breeder like that.

Any ideas? oppinions on this subject?

 

[mew]

well. good responsible breeders are supposed to cull defects like that. -_- sounds like the breeder he got them from isn't very responsible.

also, good breeders check their lineage and try to mix in wild caught strains.

 

[BigandUgly]

With good specimens there is very little risk of problems with inbreeding, providing the offspring are properly culled. The problems with captive breed fish doesn't come from the fact that they were inbreed, they come from the fact that the inferior offspring of inferior specimens have been continually used. For the most part commercial breeders are concerned more with the quantity of fish they produce than the quality of fish they produce.

Think of it like this, if mom fish and dad fish are both perfect tens, there should be some perfect ten offspring. There will also be some seven, eights and nines as well. If you only use the nines and tens for future breeding, the quality of the stock will remain high.

Now, if you take two of those sevens and mate them, the best result you will get is some more sevens. There will however be some fours, fives and sixes thrown in. Pair up those fours and the best you'll get are some more fours, but with twos and threes thrown in.

Many of the commercial breeders are letting those twos and threes mate. The best we can hope for on the market are twos and threes now. It all goes back to letting those original sevens produce offspring.

I understand this is a very simplistic thought on the subject, but I think it is an accurate portrayal of what is happening. The situation is worse on the freshwater side, since captive breeding has taken place for so long, but it is going to start on the saltwater side soon. It will most likely have the biggest effect on the easy to breed, popular saltwater fish. I would suspect we'll see it first in clown fish, but who knows for sure?

 

[phil519]

Probably should go in the responsible reefkeeping section.

But my 2 cents are this:
#1 Is there a possibility the fish were damaged versus in-bred? I was at my favorite LFS and the "MAC-Certified" CCB came in missing an eye. We were surprised...but it's possible mishandling along the route caused it. Just throwing out there whether these clowns were truly impacted due to breeding.

#2 captive bred fish are far superior to wild-caught fish for the simple reason that we are creating an opportunity to relieve *a little* bit of the ornamental fish catch happening to supply this hobby. Those same 2's and 3s mentioned previously result in the "Misbar ORA clowns" or the "semi-picassos" etc.

 

[meredith1985]

i'm not worried about that guy's one -eyed fish (he loves them). my whole point to this thread is to discuss and explore ideas on wether or not inbreeding our fish could end up resulting in unhealthy and disfigured animals. I totally support captive bred fish and would like to also support everybody out there that is trying to breed fish. I'm just trying to get oppinions and hold a conversation about the possiblities of the effect inbreeding could cause.

Inbreeding in any other animal has caused all kinds of defects in them, why wouldn't it cause defects in the fish we are breeding? I kinda think it's important for the home breeder to realize that they shouldn't let their fish's babies mate with each other and then trade them into the LFS or sell them to friends. I think they should pic their best babies and find somebody else with a high quality pair and try breeding those. If everybody is aware of it, then they can make the concious decision to keep their gene pool as diverse as possible.

 

[phil519]

valid points!

I was thinking of how finding nemo impacted a lot of people in how clowns are procured. Typically when person walks in with dollars in pocket, they will purchase two clowns out of the same tank - when it's quite likely those two clowns were derived from a single pair.

That stated - if you scan this forum - you will see very few and far between threads. In our club - we've got tons of people who are fantastic coral growers, clam keepers, etc but you could probably count on one hand the number of people who have attempted breeding fish. The old adage to make $1 million in aquaculture, you start with $2 million is so true.

I guess I don't see the kind of rapid decline in fish genetics on the saltwater hobby side due to the extremely high costs of breeding sw vs fw. I see greater risks for this hobby in releasing ornamental fish into the wild where they should not be (case in point - the Lionfish in the atlantic).

 

[meredith1985]

also very good points. Breeding fish isn't lucrative enough for this to be a huge problem yet. but I see it growing faster and faster and for every person who buys that pair from the store with the entention of breeding them. there is that much more risk. Especially if they are successful at it and sell theirs to the stores. Then that store is getting inbred clowns that will probably continue to be inbred between the brothers and sisters of that first group. it could quickly go downhill for those fish.

 

[BigandUgly]

The average aquatic hobbyist wants to be certain that the fish they purchase are as healthy and strong as possible and to do this they want a fish that comes from as diverse a family line as possible. Their thought is that since inbreeding can cause so many problems, the best fish will come by breeding fish that are as unrelated as possible. While this belief is common, and many people can see the supposed logic in it, it is not based on science and is actually quite inaccurate. Inbreeding fish will not lead to a lower quality fish, providing it is done properly. In fact, proper inbreeding will result in a much higher quality offspring.

Remember that genes can be dominant or recessive. If two copies of the dominant gene are present the dominant gene will show up. If one parent has the dominant gene and the other has the recessive gene, normally the offspring will show the dominant gene. Finally, if both parents present the recessive gene the offspring will show the recessive gene. By using a diverse breeding line with lots of outcrossings you can ensure that the recessive genes will never show up in the offspring.

This is where people get confused. People automatically assume that recessive genes are bad and we should do everything possible to eliminate them. The truth is that recessive genes are sometimes the ones that produce many of the traits that are desirable in aquarium fish. Sometimes the dominate genes are what produces the non-desirable traits in fish.

Now, if you have two fish that are "œperfect" in every way and they have the "œright" dominant and recessive genes you should breed them. Some of their offspring will be further "œperfect" fish with the "œright" dominant and recessive genes. Breeding the "œperfect" offspring with each other will continue to produce some perfect fish. These perfect fish can be continually breed down the line for an unlimited number of generations, providing that only the "œperfect" fish are allowed to procreate with each other. Keep in mind, only a small percentage of the offspring will have the "œperfect" genes. These are the only ones that should be allowed to multiply. The others should be culled, or at the least, not allowed to procreate. Eliminating inbreeding and using a very wide array of fish to breed will result in a large quantity of average fish, but no real "perfect" fish.

Most commercial breeders are concerned with creating the greatest number of offspring possible. What happens in practice is any two fish are allowed to produce offspring. They have both good and bad genes. That offspring is then allowed to produce more offspring and so on. As generations go on the "œbad" genes build up and the line gets worse and worse as things progress. The problem doesn't come necessarily from the inbreeding, it comes from the inferior genes of the parents and using the "œwrong" fish to inbreed.