Cloudy Water after Meds

[Patti-Mc]

I have a question or possible problem. I have 5 clown loaches that I've had about 7 years and one smaller one that I've had about 2 years. They are in a 75 gal tank along with 4 or 5 incidental fish. I am using a canister filter (Filstar) and one Biowheel HOT for additional surface movement. The water parameters are usually pH 6.8 to 7.0, a little hard, nitrites 0, nitrates about 30. I do a 20% water change every other week.

I've been noticing for about 3 months that not all the clowns come out to eat - but it comes and goes. One week it might be these 3 that eat, the next week it might be the other three. Then, my little guy quit eating totally and he's now so skinny I doubt if he'll make it. Also, the 5 bigger clowns are all showing some discoloration, but not all the same. A couple have brownish "stains" along their lateral line, but patchy lightness along the top. One looks patchy all over, one looks totally fine. The little one's color looks fine too.

After studying this forum, I began to believe that I have velvet disease in this tank (someone had pictures identified as velvet but I could never find that post again). I also thought that the small loach might have the internal parasites although usually with skinny disease, I thought the fish still ate, but wasted away. This fish has not eaten for weeks.

Based on all of the above, and according to several posts, I decided to treat with Maracide, Maracyn and Maracyn II. I cleaned the tank pretty thoroughly before treating. I gave the recommended dosage of the antibiotics for 2 nights, and I gave half the recommended dose of the Maracide for the same two nights.

The next night which would have been day 3, I noticed the tank clouding up. I kept watching it and within 2 hours, I could not see to the back of the tank! Then I see all the clowns with fluttering gills, acting real agitated, and the other fish gasping at the surface. Because of the speed of the clouding, and because it had been 24 hours since I'd put any meds in, I immediately thought that the biological filtration had died off.

I then hooked up a power head for aeration and put fresh charcoal back in the filter. The next morning, I ran a diatom filter for about an hour which made a really good dent in the cloud. Now it has clouded up again, but not as badly. The nitrites and ammonia both test 0. I've been checking for a nitrite spike, and maybe it would be there except that I also put a new Nitra-Sorb pillow in the filter that same night.

Does anyone have any advice or thoughts about what is going on in this tank? Sorry for the lengthy post. Thanks for any help.

[Jim Powers]

Maracyn 2 can cloud the water during use.