Plecos ( sucker fish) keep dying

Question
When we got our 125 gallon fish tank we cleaned really good several times because it use to be a saltwater tank. We have 4 black mollies 1 platey ( the other died), and a variety of chiclids. We have 4 live plants. We have gone thru 5 or 6 sucker fish. They keep dying. Do you know what would cause only these to die within 3 days of getting them?. Also, what would cause the water to get so cloudy? We have cleaned everything in the tank sevea times ( no chemicals were used in cleaning). We have tried the chrystal clear stuff and start right. They seem to make it worse. Our tank looks like there is a cloud floating in it. We have even used one of those gravel vacuum cleaners. Done water changes brand new filters and still within a day of changing out the water and putting in new filters the water is cloudy. Any advise is very much appreciated. Thanks, Rachel

Answer
Hi Rachel,
Sounds indeed like a pollution problem and resulting bacterial bloom. Since your aquarium is likely a very recent setup. The good bacteria, also know as the "Biofilter" has not yet established and the result is polluted and cloudy water, and also fish loss.

It takes most aquariums about 6 weeks or so to fully cycle. During that time fish in the tank are subject to dangerous ammonia or nitrite levels since the good bacteria are not yet established well-enough to convert these harmful chemicals into harmless 'nitrate'.

You can test for all three levels and in healthy aquariums they should be as follows -
Ammonia-0
Nitrite-0
Nitrate-15 or less

Most petstores will test your water for free.

But having test kits at home is very helpful.

I highly suspect that the reason your plecos keep dying is due to pollution in the water. Oftentimes, plecos and other catfish are more sensitive to ammonia or nitrites in the water than other fish.  And whats worse is plecos produce a lot more waste than other fish.

I'm not sure what routine you go through when you do clean the tank but remember that the best way to clean it is simply using a gravel vacuum. Theres no need to do a severe thorough cleaning.

Chemicals and tablets that claim to clear the water have never worked for me in the past. The best and safest way to clear your aquarium, help your fish through the cycling process, and allow your biofilter to establish is with daily 30-50% water changes. Remember to always use water conditioner with new water and insure the temperature is equal to or just a little bit warmer than the tank's temp.

It takes patience and persistence when trying to clear a cloudy, unbalanced tank. But I promise with water changes your water will be clear soon if you stick with it.

New filters are not necessary, your tank just needs plenty of time to get its biofilter established.

I do hope this helps and best of luck!!
Susan~