Good work! A note of caution. I don't know if you will run across this or not, I hope not, but back in the 70s when we started the first commercial clownfish hatchery (incidently our record of juvenile ocellaris from a single spawn was 953) we were plagued with a condition we dubbed "toxic tank syndrome". What would happen was that in a tank with several hundred small clownfish, we would notice that they began swimmng strangely, all bunching up and facing the water inlet, they would "shimmy" as they swam and would get very thin, as if their kidneys and salt processing capability broke down, and then within 24 hours all would be dead on the bottom of the tank. Now if we moved them to a new tank with new salt water when we first noticed the condition, then all would recover and begin eating by the next day. We experimented and moved half of the fish to a new tank, and the next day the half we did not move were dead and the half we moved were fine. The only answer I could come up with was that a bacteria, probalby a Vibro, established a colony in the tank, in the biological filter, the condition affected tanks most frequently and most virultently in tanks with biological filters, not unlike the one in your photo, that produced a toxin that killed the small fish. There was no indication that the bacteria itself was present on or in the fish. This was quite a problem for us, it was common in tanks with a lot of fish after several weeks of culture. We went to unfiltered tanks and water changes to reduce the incident of the syndrome and eventually to open systems in our larger hatcheries in the Keys and the Bahamas.
It may be as great a problem in these days of more effective filtration, good skimiming, massive carbon filtration, ozone application, antibiotic treatments, etc. but watch out for it, and if you see shimmy swimming and thinning out of the body, move the fish to a new system immediately. In some large multi tank systems the syndrome will manifest itself in one or more tanks, and the fish will survive to some extent, some dying, some hanging in there but declining in condition, and all facing the inlet and "shimmy swimming". I had problems selling fish to wholesalers because of this. Typically they would setup one tank for the tank raised clowns, and all would be well for the first shipment, and the second, but somewhere in the third to sxth shipment, they would begin to lose fish to this syndrom. I would advise them to rotate the tanks where they put the tank raised clowns and that usually corrected the problem.
You may not have this problem, I hope not, but it is possible, especially as you increase the numbers reared and and the numbers in a single system. And if you do you can work with carbon filtration, protein skimming and perhaps antibiotics (but antibiotics are a slippery slope and you don't want to have to rely on them) to reduce the problem.
Just a heads up....
Martin
