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Peter – you wrote that it could be interesting to find out at what age its possible to distinquish sex in growing young ?
I took these photoes tonight of the small parvulus, – 🙂 .. well, they are really young but its quite clear to distinguish this one. I leave the whole photo unedited, because you can compare with the other fish in the tank beside (which by the way is also a young fish, not mature size)
They are so cute – the tiny parvulus.
Unfortunately its difficult to say the age, I wish I knew but I dont.
Helene: That’s remarkable an observation and photo indeed. I have never seen a parvulus as small as this one and nevertheless bearing the full colouring of a male.
On the other hand: The P. parvulus are indicating the sex earlier than other Paros, this is well-known. But your observation of a full-colouring again is a clear sign of a special sub-group they form together with ornaticauda. The results of the genetic analyses by our friend Lukas Rüber confirm that hypothesis of Hallmann’s and mine, that those two slim species are genetically markedly differentiated from the rest of the genus. It could not be excluded but – on the contrary – it is highly probable that they belong to a sub-group of Parosphromenus that really is a sub-genus; I once called it – not in severe a mood, but a bit ironically – “Para-Parosphromenus” or “Pseudoparosphromenus”. (If the name of the genus would not contain the prefix “para” already, this would be the right occasion to use it). Whether it is a different genus indeed and how to call it I leave to the ichthyologists, of course; one should not play with these things. But many signs lead into that direction (take the head-up display or that remarkable display dance which is not matched by anything in the other species).
Your observation confirms that hypothesis again.
Peter Finke
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