Hi there.
In my experience it is not ‘common’ for paros to loose their clucthes of eggs, and its not a particular feature with certain species. If it happens, there could be many reasons why, – main thing the composition of the water. Also, leaving a cave is not a thing which could be more connected to one species than the other.
In my experience p. parvulus for example perhaps could even be one of the species which stays very much in the cave once they have taken one. Male paros are really excellent parents in most cases, staying paitiently with the eggs untill they hatch and staying patiently with the small fry untill these become too eager free swimming and leave the cave. At that point, – there nothing even a good parent fish can do, – the fry leave the cave, and they are pretty vulnerable if there are any other fish in the tank, sometimes even just the other parent is a threat.
So no matter what species you may be having, the idea of darkening the tank, to me is not really that helpful. But of course, – with a paro tank you would always be talking about a rather dark tank, with little light, and perhaps a lot of floating plants which would hinder light. And that is definitely a good thing, – small fry needs a good protecting for sure.
And just for the record, – I understand that your username is just a username 🙂 ..
Keep asking questions about all the things which may be new to you, – this is how we learn things.
Its seems you live in America, – I find it interesting if you do indeed have someone over there who can supply parvulus, – even if it may be true it can be a challenging species (mainly in terms of being successfull with the breeding, eggs needs really lower ph than other species) – but its interesting if someone does have parvulus in US. I know that a user here, Ted, used to have it, but then it dissappeared, – and we tried to send some when Bill little was here in Hamburg, – I am not sure we succeeded. But I know another person in US who wanted very much to aquire parvulus, (David Jones) – so even if you decide to wait a little, its really valuable information, and I would like to follow it a bit if possible. It must somehow be possible to get in contact with the breeder you are mentioning, ? it doesnt seem one I know. You can write me a private message if you like regarding name and perhaps an email. I find it really interesting 🙂
🙂 .. correction, – I actually have found the person you are mentioning, – and she is also a member of P-P.