HI I just started stocking my 75 gallon tank and I have a school of 6 porkchop rasboras and 5 Boeseman Rainbowfish. For the first few days they were all happy together and now one Rainbowfish has the whole tank to himself and the other rainbows are stuck by the bubble wand. The porkchops don't seem to bother the rainbow fish that is being aggressive but swim in a tight school. The aggressive rainbow swims in a circle around the tank then goes over the the remaining 4 and terrorizes them. What can I do?