which fish are most tolerant

[bolk]

I have a 35 gallon tank which I've had for a number of months now. With weekley water changes of approx. 10 gallons the nitrate level seems to hang at around 20. In this tank are two plecos, two p-sharks and two rosey barbs.
I've added other fish in the tank over the last month or so and they have all rather quickly died ( within a couple of weeks). Have I simply chosen types of fish that can't tolerart this nitrate level or am I missing something. The other fish I've had are clown loaches(2), bala sharks(2) and most recently small anglefish(3).Each time I've checked the water and found the nitrate level to be at 20 or less. Do I need to maintain a lower level to have these fish survive.
Thanks
Barry

 

[talloulou]

Generally when any new fish added to your tank dies it means you have old tank syndrome. However if you really do weekly water changes and have an ammonia and nitrite reading of 0 with nitrates at around 20 then you shouldn't have old tank syndrome. Are you buying your fish from far away? Is the ph in the store and the pH at your house similar? Are all the fish that died from the same store?

It's also unusual that the fish die in a couple of weeks vs a day or so. Maybe your other fish are picking on them? What exactly are p-sharks?

In any case clown loaches and bala sharks wouldn't work in that tank long term regardless. A pair of angelfish should do okay. Have no idea what you mean by p-sharks though.....so more info is needed in that regard.

Two plecos is also quite a heavy bioload for a 35 gallon. What type of plecos? Most likely you'd be better off with just one and if the plecos are common then eventually even one will outgrow the tank.

 

[Ichthyologist]

20ppm is an absolutely acceptable level for most all types of fish, including all you have listed thus far.

 

[Blazeherd2306]

If by p-shark, you mean paroon shark like this:

http://www.fishbase.org/Summary/SpeciesSummary.php?id=6193

You might want to reconsider keeping a shark that can grow to 10 ft long. I don't think anyone has had to worry about one getting that big....they usually die young.

But if you have a large, heated pond, then go for it lol.