Fish can grieve
I've always assumed fish could grieve, like any animal, but I'd never actually witnessed it until today.
When I first started fish keeping 4 and a half years ago I started with platys. Needless to say by the end of the month I had many more than the four I started with. I was quick to separate the male from the females though and thankfully and I didn't end up with too many babies. I kept some but most went to a friend's pet shop.
Today only three of those babies remain. A female called Sunny who lives with my betta girls, and two brothers called Bill and Ben. Bill and Ben are always together. They are in a 120l tank but they are always side by side or chasing each other up and down the glass. It's rare to see them apart.
They are old at this point so I knew this day was going to come eventually. Bill has been slowing down for a while. Less chasing and just content to eat his food and rest. Pretty sure he has gone/is going blind too. Well, in the last few days he started to chase Bill away which is very unlike him and today has developed Dropsy (poor boy is inflated like a balloon). He won't last long now, his lying on his side and will probably pass in the next couple of hours.
That brings me to Ben.
Ben refuses to leave his side. He is sticking so close to his brother. Every now and again he will nudge him to try and get him to start swimming again. It's definitely nudging and not biting. I thought he was biting him at first but when I took a closer look Ben is gently pressing his face to Bill without any mouth movement. I feel so bad for him! He is still there now beside Bill.
Fish certainly can grieve