Originally Posted by
Willie
Six weeks into it and this has been quite a learning process. Kudos to Al for a brilliant idea. I've raised many batches of fry over the years, but frankly never paid that much attention to individual fish. Raising ten meant that you looked at each fish. Al had made an effort to ensure we all received a representative sampling of his spawn so it was reasonable to assume that we started off with the same genetics. Differences can be mainly ascribed to environmental effects, e.g. raising fry.
When I started this contest, my assumption was I know how to do this and I'll just do it that way. My presumption was that it's hard to improve on daily 100% water changes. But the contest allowed me to compare my results with others and assess which approaches were better, which were not. Looking at pictures of Bryan's fish was also a humbling experience. So here's what I've learned, mostly from his results.
There were two major differences in Bryan's approach: he made 2 water changes daily and he fed flakes. So why would 2 water changes on such small fish make such a big difference vs one daily? My guess is that discus fry are very, very sensitive to nitrate levels. I don't do any measurements, but I suspect that 10 - 20 ppm of nitrate is growth limiting. Fry breath very rapidly, so these are ammonia factories. With the kind of overfiltration I do, I know that there was no ammonia or nitrite in my water. I also wiped down the tank bottom daily so bacterial buildup was minimal. So the frequency of water changes at the very beginning is as important as the volume. In this way, those who moved their fry into larger tanks earlier achieved similar results - lower nitrate levels.
Moreover, Bryan's male and female discus (I'm assuming he has both) did not differ in size. Everyone else's spawn had markedly different sized fry. My guess is the female fry are much more sensitive to nitrate than male fry. Keeping the nitrate down meant both sexes could grow closer to their genetic potential. I've seen this before with a good friend raising my fry. He made 40% water changes three times a day and produced spawns with no size differences.
Finally, the most startling conclusion was that Bryan's large, frequent water changes affected the height and roundness of his fry. Most other people, including me, had fry with bumps on the forehead, beaky fronts, football shapes, etc. In my experience, some such fry will grow up into round and tall discus. But Bryan's pictures showed that large, frequent water changes can get you there directly. I had also seen this before with my friend, but had assumed it was superior genetics. Bryan's results showed that environment was as important as genetics.
Lastly, Bryan fed flakes while everyone tried wet and dry foods to power feed their fry. Obviously flakes are just fine for raising very nice discus. I've seen adult discus that were raised on flakes for their entire life. They don't have the "side of beef" look to them, but they grow up to be beautiful fish.
So far, a great experience for me. I will raise my spawns very different going forward. I only hope that these contest threads get read by others not in the competition.
Willie