Growing strong and healthy fish

[raymond82]

With more and more fry growing up, it also becomes more and more important to think of how to get rid of them. I have already found a couple of shops that are willing to take my juveniles, but of course I want to be able to offer them good quality fish.

Today someone told me that getting young fry used to our local tap water makes strong fish. That could be, although I think there are more important factors contributing to the health of fry.

So: what are the most important things to look at/take into account when breeding fish?

 

[Mike Wise]

For me it is quality: high quality breeders, frequent feedings of quality food, frequent water changes to keep water quality high, and aggressive culling for only producing quality fish.

 

[raymond82]

Frequent feedings and water changes should be relatively easy to do, but the culling is a different story. What characteristics would make you cull a fish? Even more general: how do you recognize a good quality fish from a lesser quality fish (in particular among fry/juveniles)?

The resilience of fish is probably a good readout for the quality of the fish, Betta splendens for instance always appear quite weak to me but this is probably a result of too much inbreeding.

 

[slimbolen99]

Water changes, water changes, and more water changes. I'm currently in the process of reworking my fish room into a situation where I can make water changes almost completely automatically; and doing as much as 50% water change everyday. A friend of mine uses this same system and grows out huge numbers of fish in relatively small setups.

Live foods are a big bonus too, especially for apistos; live california black worms, mosquito larvae, and baby brine shrimp are some of my favorites.

 

[raymond82]

Fair enough, looks like the key is water changes... Now that I'm thinking about it, water changes are a little problematic in the sense that I cannot produce and store that much RO water. For fry, would it be OK to have them grow up on tap water (in my case KH8 and pH8, conductivity 420 μS/cm)?

Live food are no problem, I feed BBS, microworms, grindal worms and mosquito larvae. I've also managed to get some juveniles to eat Repashy food, is that of any additional value?

 

[FIL]

What is aggressive culling ? i don't understand this expression. It is a selection of fish? it's very difficult to do selection when they are young

Nicolas

 

[Mike Wise]

By "aggressive culling" I mean removing any fry that appear deformed, much smaller than most of the spawn (runts), or just don't look right (based on experience). When I cull, Mugsy (my 16"/40cm Electric Catfish) gets a treat. It's a quick death for the culled fish and nothing goes to waste. I usually start culling fry at about a month of age.

 

[raymond82]

I have never seen clear deformities, I have seen fry that was smaller than others (the term "runt" is new to me though). Then again, I don't have much experience so I could have missed some.

My main worry was about weakness in fish that is not apparent from the outside, but would show for instance as reduced stress resistance. I thought that this was what people refer to when they talk about "bad quality fish", not so much deformities.

 

[DBlauj]

I've seen fry with defirmed finnaged but that's about it. Would like to know what else to look out for.

 

[FIL]

As say Mike, only experience must help us to do good selections. It must time.

 

[Mike Wise]

On juveniles I mostly look for deformed fins & scale rows, oddly shaped bodies and specimens that tend to avoid the other juveniles in the tank (odd behavior). As FIL writes, it takes experience to recognize these abnormalities. I get very few abnormal specimens, not because of my 'stellar' care, but because I tend to keep wild caught fish, which show less inbreeding. If you breed more of the domestic strains, then expect more abnormalities to appear.

 

[raymond82]

Intuitively I would say that inbreeding is the major cause of deformities. Fortunately, from the 4 species I'm actively trying to breed 2 are wild caught, and one of the tank bred species already produced healthy fry so I'm not too worried. I will keep an eye on future fry though, also on their behavior and growth rate.