Hmmm...not 100% sure but if we use that old rule of thumb about 1" of fish per gallon of water...your 180 litres is roughly 40 UK gallons - so that would make about 40 inches of fish (but you have 100 inches of fish approx!). Even if we doubled that guide up to 2" per gallon, that would still make you overstocked.
The thing is that if you keep these fry in overstocked conditions for too long, it could cause stunting of their growth and then you would have problems selling them.
I don't know - I've never kept that amount of fish in one tank myself so maybe someone else will have a better idea. I mean, my fish do have fry - lots of them - but they are usually eaten off within a 2 week period when they are still teeny wigglers.
I guess for now all you can do is make sure you have the best filtration possible, do extra water changes and try to get at least one other tank set up to move some of them into, if possible.
Regards
Athena
Thanks for the reply

yeah i was aware of that the inch rule but i just wanted to see if someones ever kept them in a tank that size, Ive seen a few people who have kept around that much in a similar tank size. I just need to keep them in there for a while as i am going to get rid of most of them in a week or two.