Blues take longer to grow than Oscars, and blues aren't very hardy when they are small. Remember blues are wimps and stress very easily (and die from stress quickly)! Keep it by its self until it reaches 3 ½ inches or more and let it establish a territory. Then add the other fish. DO NOT PUT IT IN WITH THE PIRANAHA!!!bentnewt said:can i put a jack in my piranaha tank
Im not sure if an Oscar and BJD will be ok together in the long run though. But I highly recommend getting a few BJDs. They have a great color of blue, and some have golden bodies while others are strictly blue. I cant wait until mine mature.