Red Tail black sharks and plecos

Red Tailed Sharks are hostile, and generally not recommended for community tanks with smaller or weaker fish. Plecos aren't really "smaller", but certainly aren't as aggressive as these sharks are. I wouldn't do it... ;)
 
Depends on the type of pleco, and your setup. There are many kinds of plecos that will work for smaller tanks and can be mixed--the commons aren't on the list, due to their large adult size. Bristlenose, rubbernose (also called bulldog), and otocinclus are good choices that stay relatively small. What do you want the plecos for?

With sharks--they can be kept with fish that do not resemble them in body shape. Plecos wil work, but SAE, CAE, and other sharks won't mix. They are very aggressive with one another, and territorial with most other fish, so providing them with a good cave to claim is essential.
 
On a side note, these sharks can work with plenty of hiding places for other fish... but only in a very large community tank. These fish are not for the beginner, and as I said, need lots of room despite their "medium" size of near 5 inches.
 
I have a rainbow shark and a pleco together in my 29, and they don't bother each other, and sometimes they even munch on the same algae wafer together... however, I think RTBS's tend to be a bit more aggressive than the rainbow.

~Tara
 
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