dying barbs

Question
Thanks for trying Chris, starting to lose the others now. Did another few near-complete water changes, but lost a couple of white clouds today. 7 of 8 barbs dead, last one actively dying. Tank smell is off-hard to describe. Changed mechanical filters to fresh, 75% water change today. Keep hoping...

I'll have our LFS check my water as well this weekend.

Followup To

Question -
All fish in the tank look and acting normally. Gourami maybe puffing more than usual. I feed variety (tubifex, brine shrimp, veggie pellets for catfish etc) twice daily (at most) no feeding usually sat or sunday so doubtful I am over feeding. I would think also this would affect all fish equally too, not just the one species.  

Answer
Hi Doug;

Ooooookay, now we're getting somewhere...... Does the water smell like ammonia/urine? Or, more like rotten eggs? If it's a rotten egg smell you have decaying waste and anerobic bacteria in your gravel. It will put out serious toxins than can kill fish when disturbed. Get an airpump and an airstone to aerate the water more. More oxygen will kill the anaerobic bacteria as beneficial bacteria takes over. If you have decorations in there, remove one and see if there is crud in the gravel under it or if gas bubbles rise from it. If so.....stop! Get your vacuum and suck out that gaseous mess before it kills more of the fish. If you have to, net the fish out for an hour or so to an aerated bucket of aquarium water and get the tank clean. Remove all the decorations and vacuum thoroughly.

Changing the filters is actually a bad idea. It removes beneficial bacteria that removes ammonia and nitrite. Only rinse filter media. Rinsing will preserve most of the bacteria but gets rid of the crud that plugs things up. Keep rinsing them periodically until they literally fall apart from age. I have some in my filters that have been in use for years.

Let me know what you find in the gravel.

If my question load is maxed-out, write to me here;

chrisrmail@yahoo.com

This problem is too serious for you to wait for the next day to get your question to me......

Chris