New Gold Fish Nipping At Each Other?

[Raechal]

So I have a ryukin goldfish, an oranda and two black moores in a 55 gallon. and we just added the ryukin and the black moore today. The Ryukin seems to be chasing the oranda around and looks like he is nipping at his fins. is this normal for just adding a new goldfish or should I be worried?

 

[Sandusky]

That's breeding behaviour and new tank member behaviour. Before you added the new fish you should have rearranged the decor to eliminate established territories, but now just take them all out and move everything around, then put them all back in.
If the fin nipping persists it's more than likely breeding behaviour. Males will have turbricles (sp?) small white dots, or stars, along their pectoral fins and gill plates. These resemble ich (but are not) because they are soley concentrated in the mentioned areas. In this case watch them closely, if there is any major damage then remove the chasing fish. Otherwise they should be fine, 4 goldfish in a 55 is plenty room for swimming away. Just remember that the maximum number of fish in a 55 is 5.