In my 29 gallon fish tank i have 1 rainbow shark and 1 paradise fish?

Question

i want to add couple of congo tetras.how many should i add?are they compatible?i want to add somethin else to the water.is there small specie creyfish or would something else be better?i dont really want snails so those i dont really like.any suggestions would help alot.

Answer 1

Paradise fish can be aggressive, so I'd be cautious about adding anything else while he's in there.  Also, congo tetras are pretty big (mine are almost 4 inches long from their heads to the tips of their tails).  And since they like to be in schools of at least 5, they'd be pretty cramped in a 29 gallon.  I keep mine in a 55g.

There's plenty of other beautiful fish you could keep in your 29g, though.  Just be prepared to move your paradise fish if he gets aggressive.

[edit] Serpae tetras are smaller and hardy, as well as colorful.  A small school of them would work nicely for your tank.  Lots of other tetras would work as well, among other fish.  Here's a site that has lots of info on different fish and their tank requirements:

http://www.liveaquaria.com/

Answer 2

                            pH               Temp in F

Rainbow shark     6.5-7.5          75-80°

Paradise fish        5.8-8.0          65-80°

Congo tetra          6.0-6.5          72-82°

   Should be kept in groups of 6 or more, so a 30 g     tank is minimum for them, and only them.

I've read diverse views on the paradise, some recommending no less than 30-40 gallons.  I'm not sure if this is for just one, or in a community tank.  I've successfull kept one in a  gallon container with no problems.  At 4" full size that would push it, and mine weren't "growed up" yet.  I believe it would be fine with your other fish.

Crayfish should not be kept in an aquarium as they will catch and eat your fish.  A bristlenose or clown pleco would work.

Again, with this size tank, congos are not recommended.