We have a Jack Russell of 5 years old. I have recently moved in with my girlfriend, and I brought with me two large fish tanks. 'Buddy' the JR now has an unhealthy obsession with one of the tanks and stares and growls at it non-stop all day, sometimes building to an uncontrollable frenzie from which it is very difficult to drag him away from. Very uncharacteristic for him.
I don't think the behaviour has anything to do with me moving in, since I've pretty much been living there for months anyways, and Buddy and I get on brilliantly.
He is also aggressive to some dogs whilst out on walks, in particular black dogs and pitbulls. Buddy was a rescue dog, and has several bite scars on his head.
We are desperate to solve the fish tank problem as soon as possible, and prepared for a long slog to correct the other behaviours.
Your help would be appreciated!!!