Good Morning, Peter,
and thank you for your detailed answer.
Yes, I think you are right – your suspicion corresponds with my own impression that the female might have stolen some eggs…………
As I said, the male is sitting in a “cave” near the ground formed by arching leaves. I am not able to look inside, not a single glimpse is possible, it’s totally in the back of the tank. I am sure they mated and spawned like they already did before.
The morning after I posted my observation I still saw the two tiny fry hanging under the ceiling of the cave. But suddenly the male appeared and swam into the cave. I watched him closely to see what he would do – and I am afraid what I saw looked like sweeping the cave by forcefully swaying his caudal. It took just half a minute, then he left the cave and returned into his own hiding place. The two “stolen” fry were gone …………
I find this quite interesting. I doubt that he recognized the fry as his own. To me it seems more like competitive behaviour: He discovered “someone else’s” fry in the surrounding of his own territory and got rid of it.
I know that such behaviour (a male killing the offspring of rivals) occurs in many different animal families – is it known from paros?