yuffie

Hi, I have an 80L tank with the following fish in it: 5 neon tetras leopard pleco catfish 2 angelfish rainbow shark 2 male guppies male betta Everything seemed to be going ok until I got the male betta and I've started noticing fish tails being bitten and I'm not sure which fish are causing the problem. First I noticed that the shark and the guppies had a small chunk missing from their tails. The next day I saw that the betta had a split in it's tail. A couple of days later one neon had a chunk out of it's tail, the betta's tail was worse, and the larger angelfish had a split tail and was missing half of one of it's long fins. I don't think it's fin rot because the fish with damaged tails have just suddenly had the tails split or chunks taken clean out. I watch the fish all the time and none of them appear to be very aggressive except for the larger angelfish which sometimes chases the smaller one around, but then I don't know what has bitten the larger angelfish. Any suggestions what to do please? I hate seeing all my fishies losing their tails