Hostile shubunkan goldfish?

Question

Ive had two small goldfish for a while now about 10 months about two weeks ago I decided to get another one He is larger than the other two probably about twice as big and I asked the store if this would be ok and they said it will be fine as they get on with all other goldfish but I noticed recently the two smaller ones fins are all deformed looking,realising it must be the bigger one eating their fins I took him out but a few hours later one of the smaller goldfish died noticed they had white spot as well ,why would the bigger one start eating their fins if there meant to be non hostile fish? Maybe he/she was a different s*x ,lack of food maybe? (i did give them a small pinch of food every day or so) I'm presuming the smaller fish died because it was so streesed the bigger one was eating his fins.

Answer 1

Few things going on here.  Once small pinch of food for even two goldfish isn't enough.  Goldfish should be fed 2-3 times per day not once every other day.  There isn't enough algae for all of them in the tank.

Secondly, adding a larger variety of goldfish like a shub places a tax on your biofilter.  This could have caused ammonia spikes causing the fins to look rotten or deformed and not necessarily from the shub.  Due to this the fish could have become stressed where as ich attached itself to your fish.  

Part of fish keeping is you need to observe your fish every day.  Feed your fish daily and watch them.  Have you tested your water lately?  I would test and do a water change.  If the fish were in the tank, the entire tank now needs treated for ich.