White fluffy stuff floating in tank

Question
Hi Chris,

My tank (60 gal.) has developed a bunch of white cotton like stuff floating in the tank as well as sticking to plants, rocks, gravel and the filter sponge.  None of the fish (3 adult Convicts, 4 baby Convicts, 1 lg. Oscar, 1 med. Pleco and 1 XL Pacu) seem to be affected, but the stuff just looks nasty!  Any idea what this is?  How do I get rid of it?  My tank has been established for almost a year with very little trouble.  The nitrite and ammonia levels are stable and the Ph fluctuates with water changes.  I keep the temperature steady at about 79 degrees.
Thanks for your help!!

Answer
Hi Kim;

The white stuff is from a bacteria known as saprolegnia. It looks like fungus and is feeding on excess food and waste. Your fish have probably been growing for the past year and are producing more waste. It's easy to overfeed such large types of fish too. Do some major vacuuming to get it all out of there and cut back on food. It can infect your fish, especially tender areas like the gills. Resist the urge to drain it all and start over. The tank will go through a break-in period and that would be more stressful and dangerous to the fish than vacuuming it out. Just replace 25% of the water while vacuuming it about twice a week for a couple of weeks. This does the job gently without disturbing things too much.

They really are going to need a bigger tank soon. A 60 gallon is really only big enough to house the oscar and pleco as adults. Your oscar and plecostamus will each grow to over a foot long, and pacu get at least three times that size as adults (over 40"). By that time your convicts will probably get eaten. In spite of tank size, your fish will just get bigger and bigger and begin eliminating each other. Convicts will probably be the first to go. They are pretty hardy and scrappy little fellas, but it's hard to fight something that can swallow you whole. Yikes! It will take a few months, but don't wait too long. Not tryin' to be bossy, just concerned. ;-)

At Your Service;
Christine Robbins