Sharkie the black shark was downgraded almost 2 months ago from 1800 gal to 240 gal. In the first weeks it had been receiving a non-welcome from the common pleco resident, which would chase it away from its whereabouts, especially during feeding, by trying to suck up to the shark, and the shark would escape quickly without answering back. Nowadays all is well and the pleco doesn't bug Sharkey in the past weeks, not that I noticed anyway.