Something might have startled him and he whacked heavily into something, doing the damage you see.
Pop eyes on their own suggests an internal infection but the other with it makes me lean more towards injury.
Keep a close eye on the injured area for signs of secondary infection (ie fungus)
They could have eaten it in 4 days. I am not sure how fast goldfish eat others but tropicals can totally devour a body overnight!
What size are they all?
Was someone feeding them? Surely they could tell you how long it has been missing?
Depending on when it died it could have been consumed.
Jumped out of the tank (look for a mummified fish).
It died and the people feeding them threw it out figuring you wouldn't notice it was missing.
I am going to have to come and visit you :lol:
Where in Ireland are you? We are planning a trip to Scotland so could venture a bit further afield while over there
I have to wonder about the mentality of some people. If my mother did that I wouldn't hate her, I would be concerned about how she felt as I am sure it wasn't deliberate. Grow up guys and show some empathy towards others.
I wouldn't put convicts in with anything! Worse than rabbits. Known as the "just add water and they will breed" fish. Only need a small amount of it too :lol:
Mine were more vicious than yours Anna_&_Chris and they attacked anything that moved - including other convicts.
I have always found these fish will breed if they want to, or not if they don't, regardless of conditions :roll:
They particularly favour tight spots in, or under, driftwood.
Just a bit bigger than the fishes. Doesn't have to be huge. Most fish prefer a tight fit (within reason). The size of the opening is more important as they can more easily defend a small one from predators.