Thanks for responding... of course I have done all the things you said not to in the interim but it seems to be ok. the group as a whole is actually doing really well together. No fin nipping, no chasing (except between male and female barb when she's getting ready to lay eggs). The betta's dorsal fin is completely gone and I imagine it had to do with the water in his small tank--it probably hadn't been changed recently before I got him and I hadn't changed it during the week I had him... The progress seems to have stopped and hopefully it will heal with better water in the big tank that he's in. I think the size of the tank and the plantings are helping keep things quiet, or I am just lucky, or they will now start chasing each other It's just the 3 danios, 4 barbs, betta, and an algae eater, and it's going to stay that way so crowding shouldn't be a stressor.