Do senegal bichirs (polypterus senegalus) like to live in groups? I had two that always swam around together and slept by eachother, then one jumped out of the tank a few days ago and died, and now the remaining one just kinda wanders around the tank or lies in corner. Does he miss the other one? Should I buy him another buddy? Or do they end up getting territorial and wanting to be alone as they age? The bichirs are/were about 3-4". Thanks!