wat do u mean by outdoor aquarium?? If the aquarium is place outside instead of your house, it will be extremely dangerous. There alot of wild cats roaming in the streets. They may not be able to reach the fishes but if it continues to paw the glass the fish will get shock from that.And also make sure u take note of the ph of the water . The more fish means more waste material.In the end ur tank will be loads of fish waste if u dun clean it.And... usually females after reproduce need to be separate or else the males will keep on stung her.