I put about 50-60 week-old angel fry into a 20L growout tank on Monday. I added 6 cory pygmeus to the tank to eat excess bbs. Yesterday there was about 8 dead fry and only 11 live ones? What happened to the others? The cories are tiny, there's no way they could have eaten any live fry. Maybe the fry died and were eaten by the cories? Confused to say the least.