tanks size

Question
I am getting a 55 gallon tank I already have a bala shark and two rainbow sharks how many other bala and rainbow sharks can i put in there i was hoping for 4 of each and possibly some other fish also what do I do about the nitrite cycle do I put my water and old gravel in along with biosphere thanks alot

Answer
Your 55g is too small for an adult Bala and Rainbow sharks are best kept on there own.  When the rainbow sharks reach maturity they will start fighting and the weaker one will die.  If you are setting up the 55g you will need to cycle it.  The old gravel and biosphere will help the process and it should take less time then normal.  If you are going to keep the Bala, you will need another tank and you should probably separate the rainbows.  Also, be careful not add any other "shark like" fish.  Rainbows and red-tailed sharks do not get along.  There are certainly lots of interesting fish you can keep with your shark in a 55g.