I have 3 cichlids and lately when I come into my room to feed them I notice that my blue one will swim up to my red one and the red one will start to almost shake. It almost looks like it's having a seizure. They don't ever look like they're fighting, although I know that cichlids are aggressive and territorial. My yellow fish, which seems like the most aggressive and territorial one will sometimes dart after the red one and the blue one will get between them, like it's trying to defend the red one. I just don't understand what the weird shaking is all about.