Just added a silver arowana in with my black aro. Wondering what I should look for. When I first added it the black bit the the silver a couple times but it didnt look like serious biting and now the silver occasionally bites the black but not serious bites ????? So what could this mean? are there such things as play bites with fishes?? I dont want to lose my black the black is smaller than the silver.... and what can I do?