Only domestic fish do it, so I thought it might be analogous to horses' cribbing, but as you say that wouldn't happen in Rainbo"s tank.
A while back I went to a conference at NYU''s center for Mind, Brain and Consciousness - in animals. The speakers and topics on FISH were so interesting. The whole thing was recorded and can be viewed on NYUTV I just have to dig up the link.
If we assume fish are sentient and have Consciousness (and that was the gist of it) not to anthropomorphize but it's not a stretch to think them capable of boredom, depression and even perhaps certain "neurotic" behaviors.
Not to go too far off track but it was proven fish experiencnce REM sleep (I'll hunt down the link, promise) so I had to wonder - do fish dream of aquatic sheep? [emoji207][emoji207][emoji207] [emoji2957]
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