a bit of backstory: i got this Angel a year ago at about 3 months old. i bought her in a pair. about 6 months into having the two, i would always catch the bigger one picking on the smaller one. this went on for a few weeks until one morning when i was looking at the tank and realised the smaller one was hovering low behind some plants, breathing shallow with fins ripped to shreds. that night i made the decision to rehome the bully fish and keep the smaller one. all has been well ever since. their family consisted of the one angel, 2 cory cats and a small school of glowlight tetras all living happily. about 2 months ago i was surprised with a red tail shark (not sure if that is the correct name) who was about 2 inches when we first got it, and is now about 3.5-4 inches. as far as i know, everyone gets along and the shark is peaceful. as far as i know. a few days ago i was admiring my angel when i noticed her fins looked a bit more ripped up than usual (they never fully regenerated after the bully incident). now i am concerned again. could the shark be nipping? is it the plastic plants? does she get too close to the water intake tube for the filter? does she have fin rot? i am skeptical about the last one because she seems perfectly healthy other than the fins. eats well, breathes normally, is relatively active ect. my water parameters are good, i have 36gal bowfront, 50 gal fluval aquaclear filter and feed them freshwater flakes twice a day. is there a specific food i can try that wouls help her flourish? below is a link to a video from today taken on my phone. sorry for low quality, it was the best i could do with the daylight coming in side note: my shark has been grey with the bright orange fins ever since i got it. when i research red tail shark they are always described as black. mine looks identical to the photos shown, except it is dark grey. it acts healthy otherwise - is it normal for them to not be black?