I've had my 55 gallon aquarium set up for 2 months now and all the fish have gotten along fine for 2 months, all of a sudden my Senegal bichir has killed 3 fish in 3 days. he used to keep to himself bottom dwelling but now he acts like hes king of the tank and he swims around the top attacking any fish near him. the only thing that has changed in the past 2 months is he got one of the feeders for my other fish, now he is very aggressive. What can I do to solve this problem?