When you wrote of crossing a guppy and a Gambusia in that previous thread, you claimed that you got both guppies and Gambusia offspring. Then you noted that you felt that your Gambusia female had a first drop of 300 fry.

I responded, "This may be where the confusion came in. They would be the first to agree that their record figures for most fish will be increased, but the ALA (American Livebearer Association) keeps records of record spawns for over 175 different species and commercial strains. The record recorded for Gambusia affinis is listed as 68. Their record for Gambusia holbrooki was posted as 113. (Both were registered by Canada's Jim Robinson.) None of the other 21 Gambusia listed come close to that. The only livebearer in the list with more than 300 fry in a drop was a domestic swordtail.

Here's what I think happened. You saw a pretty good sized female Gambusia dropping her fry. Probably a couple other fish, most likely guppies also dropped batches of fry. Actually there would likely have to be several batches of fry to get 300 o(n) the head. You probably have mixed guppy and Gambusia fry together.

No wonder some resemble Gambusia and some resemble guppies. That is because some are Gambusia and some are guppies. :) "

Having enough space is very difficult for all of us. That combining of pregnant females and then fry was very likely what caused you to think that the Gambusia and guppies had crossed.

Here you note that you took a virgin female painted platy and a male grey balloon molly and bred them and 1 baby was successful for a year but then she dissapeared one day(gambusia ate her)."
I don't understand what you mean by "for a year". Had you been trying to mate them for a year? Was the fry a year old when it was eaten by a Gambusia? Was the fry the "she" mentioned there?

Also, what was that Gambusia doing in there with them? Were you raising other fish in that tank during what is supposed to be an experiment?

It certainly is difficult for us having the room to do these things and I applaud your curiosity, the use of more than one tank and interest in these things. But if you are trying crosses you need them separate and the tanks covered.

This wasn't addressed but you need to make sure that plants and water aren't moved back and forth - so that the possibility of fry hitchhiking from one tank to another is eliminated. You didn't move plants back and forth over those six + months? The tanks were well covered to prevent jumping and nothing could leap between tanks?