That's roughly 20 gallons? I'd say you can fit plenty of fry in the tank for a while since they're only 2cm. I have a 15 gal (56 litre) and keep at any time up to 50 fry for my cichlids. The only suggestion I'd say is to change the water a bit more often than the usual "once per week". I usually change the water of my fry tank 2-3 per week.