what sort of blak things were they
it could of just been poo guppies usualy have a black poo before or after they have gave birth to some fry
but i need a bit more info then i might beable to give u a defonate answer. 

i'm not selling them to my friendsabstract said:you can seriously stunt their growth even if they are there for a short period of time..and the fact is they will need new homes before they are big enough to give away to your friends and what not so it would be a very very good idea to get them a bigger tank...i have a 2.5 gallon which is currently unused because i would rather keep my fry in the larger tank even though it will become quite overstocked when they begin to get a little bigger...thats when i will invest in a 10 gallon growout tank, which really isn't that expensive and is really worth it
my LFS has fully grown guppies in about a 7-20 gallon tank and they have about 20-30 guppies in there and ur telling me mine is too small compared to how many they have in one tank at a time my tank is massive.
enough my fish are very happy because they was just in a little lunch box before i can c the little smiles on there faces.
isn't it sooo anoying when people tell u how to look after ur fish.
not if there helping of coarse but this is going no where its not helping me is it.
i cant keep them in that tank when they get bigger i'm not stupid u no i have a tank ready for them when they r bigger it is a 100 gallon one it might even be a 120 gallon i cant remember and i have 25 fry at the moment
and they r all going in that and dont tell me that its not big enough for all of them because it is.
i have a thing with getting myself enemies guess i like a bit of a fight oww sorry anyway mariah and abstract.
my first batch of fryabstract said:New born: 6 mm
One Week: 7 mm
Two Weeks: 1 cm
One month: 1.5 cm
Two months: 2 cm
Three months: 2.5 cm
Six months: 3 - 3.3 cm
Full grown: 3.5 - 4 cm">>