This is more of a curiosity question about fish rather than help with anything...?

Question

Now that many of our freshwater tropicals are able to be bred commercially on farms or by dedicated fish breeders, how important are the water parameters such as pH and hardness to these captive bred fish? For example, discus need a lower pH and alkalinity than say that of African cichlids, where the opposite is true. Having talked to several fish people in my home area, which unfortunately is not very many in SE Missouri, the reaction is mixed. My water is very hard and has quite a high pH (around 8-8.2 straight out of the well), but my tetras (Hemigrammus ocellifer, Hyphessobrycon erythrostigma, Paracheirodon innesi)(all in italics of course, darn formatting here....lol) seem to be doing very well. What are the thoughts of others here? Are commercially raised fish able to withstand larger water differences than that of their wild counterparts?

Answer 1

Generally speaking yes, captive bred fish are more tolerant of a wider range of water chemistry than wild caught fishes. Really though, even for wild caught fish, it's as much a matter of conditioning as anything. As you mention, tetras can do well in the "wrong" water conditions. Personally I think far too much enphasis is placed on things such as hardness and pH when in truth they rarely matter. Fish will live, by and large, in the water they have become accustomed to and tinkering with pH and hardness often causes the fish keeper far more problems than simply having the "wrong" water conditions for their fish. I have seen farms in FL happily breeding discus in 7.8 - 8.0 water without a problem one, not to say it's always ok to do that, but it works for them.

All that having been said, a few dozen generations of captive breeding will not erase eons of conditioning to certain water conditions. Even with captive bred fish it's all the better to match your fish to your water when possible, especially with such things as Discus that are a bit touchy about water conditions.

Fish are far more adaptable than we often think. Add to that you are considering a thrive vs survive situation for some fish and it muddies the answer even futher.

Also never forget that monitor and adjust your pH is a mantra repeted all too often by the people that make and sell pH test kits and adjustment materials. Sometimes it is all about the money.

MM

Answer 2

I would say yes, while breeding itself may require a careful match of certain parameters to trigger a fish to spawn, captive bred fish are usually kept in more "generic" water chemistries. The breeders I know keep 2 to 3 different water chemistries and all their fish are grown out in one of them according to specific requirements. In the wild on the other hand there are endless types of waters... This tactic not only helps breeders but the entire process all the way to the fish store who likely have 2 or 3 separate systems at most to display their livestock.

So while there are still certain extremes to respect, such as discus needing acidic waters and African cichlids needing hard waters, most community fish today acclimate well to a wide range of PH or hardness. The acclimation process is often more important than the chemistry chosen as long as it is within an acceptable range. Stability is also often more important that the values chosen.

For stability reasons, I often suggest people make do with the PH/hardness of their tap water and choose fish accordingly rather than constantly having to adjust values during water changes.

Hope that helps

Answer 3

stability is the most important factor for 'most' captive bred fish. stable pH and hardness, and a non-stressful transition from what they are in where you buy them to what type of water you get from your tap.

It is much more important to keep a reading of 0 ppm ammonia, 0 ppm nitrite, and as low nitrates as possible ... less than 20 ppm is a common number I see, but that is still 7x stronger than normal. I have read that high nitrates may lead to shorter lives, decreased resistance to disease, and possibly a cause of Hole In The Head/Lateral Line Erosion in Oscars. Nitrates are also not healthy for human consumption at those levels either and can cause problems with babies/children/pregnancy. There is a standard ppm max set by the Clean Water Act, but I don't remember the exact figure.

Again, I don't think the fish can exactly stand larger water differences on a constant basis, but the possibility of two fish from the same mother, could go to different parts of the country and adapt to its owner particular water conditions if they remain stable.

Answer 4

That tends to be the general idea, yes. Since they are being bred in conditions that aren't their natural ones, and only the ones that survive breed...they are getting hardier, in some species.

However, some, like the Ram Cichild are getting weaker, because they are finicky, and in addition to abnormal pH and hardness, they are give hormones to 'improve' their color.