Are catfish colorblind?

Can Pictus Catfish and Rainbow Sharks live together in 10gal tank.?

• I have a 10 gallon tank, for the last 3 years I've only had 2 Pictus Catfish, and another smaller black and brown catfish I've had for 6 years that I no longer find in stores. Anyway about a month ago we got a filter. The first time we have had a working filter in probably over 1 1/2- 2 years. 10 days ago, upon going to Petsmart we decided to get some rainbow sharks. We ended up getting 1 regular Rainbow Shark (black with red fins), and two Albino Rainbow Sharks. Now on the 10th day, no one, but both of the Pictus Catfish died, well one is still dying, there must be a cause of it. I've had them for three years! Earlier today all of the fish were active and swimming around, then around 6 pm Eastern Time I came across the 1st dead Pictus Catfish, now being 8:42 PM Eastern Time I have discovered the other one is dying. Anyone know whether the Rainbow Sharks killed them, or maybe it was the filter. Maybe the Rainbow Sharks release somekind of chemical? Anyhow hints and tips would be appreciated. Note: The Pictus Catfish were about 2 1/2- 3 1/2 inches long. The Rainbow Sharks were basically babies, the black one was maybe 1 1/2, maybe. And the Albino's are not even 1 inch.

• Answer:

  All of those require a bigger tank. 55 for the rainbows and red tail sharks. 40 for the pictus catfish. You cannot have more then one red tail and/or rainbow shark in a tank. It may work for a little while when they are young but they become aggressive and territorial towards each other as they mature. You need a filter for a tank, all the time no matter what fish you have. The filter houses beneficial bacteria that will change toxic ammonia into nitrate which is harmless in small amount. Your fish most likely died because you added to many into an uncycled 10 gallon tank. I suggest googling "fishless cycle". It's important to know about that stuff if you want to be successful with fish. As for the original question, it would be risky to keep pictus cats with rainbow sharks. Pictus are generally peaceful while the rainbow sharks can become territorial and both fish share the same region of the tank.