I am pretty new to fishkeeping and hope that someone on this forum can help me.
I have two jumbo blackmoors and just rehomed them into a 170l tank. They used to live in a 60l biorb for the first month as I wasn't aware that the size was too small. They got along well in the 60l tank, no issues at all. I rehomed them 2 days ago into the 170l tank and the bigger of the blackmoors started bullying the smaller one. He basically makes it to his sole mission to chase him around and also started nibbling his fins. The smaller one started resting on the ground which concerns me.
Does anyone have any advice on this problem? Could this be a temporary issue or will I need to separate the two?
I'm suspicious that this isn't outright bullying, but maybe breeding behaviour and the large fish is male, trying to get the other one to breed. This can sometimes happen even if both are male with fancy goldfish because their rounded bodies look female. If the smaller one gets too exhausted you'll need to separate them.