Possible Velvet on Angelfish

Question
I have a 20H tank w/5 angelfish. The tank has been estabished since 2/02. The fish are in the 2-4 year age range. PH, Ammonia & Nitrite levels are all good. Tank temp is 82. One fish, a jet black veil angel has been exhibiting signs of some disease/parasite for the past several months, but several attempts at treatment have made no impact. The other 4 fish do not seem affected. The fish is lethargic most of the time, but will have spurts of activity. Its fins seem to be clamped some of the time and the dorsal fin seems 'humped' (?). The fish is constantly in a head up position, but seems to have a good appetite (it loves bloodworms!). I have just read the symptoms of Velvet and was wondering if you would agree with this diagnosis? All advice is greatly appreciated.

Answer
Hi Tim;

Velvet would be affecting the other fish as well by now. It is a parasite that would easily spread and they would all be dead after this length of time. Here is a link to a good article about it;

http://freshaquarium.about.com/cs/disease/p/velvet.htm

Watch all the fish carefully from a distance for a few minutes. I suspect that the other four are mates to each other and have bullied the fifth fish into being afraid of them. Fish bullying can be very subtle and an especially shy fish would easily want to hide from the aggressors. The fact that his dorsal fin is humped indicates he may have been trying to feel smaller and less like a threat to the others for a long time. If the humped part is the top of his head and not the fin, he is probably an old male fish.

A 20-gallon really is pretty small for that many angels. Hopefully you are making at least a weekly 25% water change so there isn't a lot of nitrate building up. (nitrAte, not nitrIte) The smallest size recommended for 4 to 6 of them is 55 gallons. They each get about 6 inches long (just body, not tails) and are a territorial fish that needs plenty of space. The taller the better too, so their fins get as much room as they need. You might consider moving the weaker one into a tank of his own to help him recover. Or, get a larger tank for the others and let the poor weak guy stay alone in the 20.

I hope he feels better soon.....

At Your Service;
Chris Robbins