A month ago, I acquired a 25g freshwater tank from a coworker, who's father hadn't cleaned the tank in about 3 years. The tank came with two full grown fish which I was told were rainbow tetras, as well as a few other full grown fish. After finding fishlore and doing some research, I have come to realise that they are in fact congo tetras. From what I read, these are schooling fish so they need at least 4 to be comfortable, but they also need quite a bit of room to swim around in. So now I'm not sure what I should do with these guys. Any suggestions?