infusoria (is that the right spelling?) for feeding small fry

[jiri8]

I had an unusually large spawn from two pairs of Gourami, and have between 1500-2000 babyfish over a week old.
From the observation by magnifying glass, I see that most of them cannot swallow the brine shrimp, and the tiny pieces which are in any of the products I have (Hikari First Bites, Wardley small Fry, NutraFin Fry Food) are also too big. Only some 10 fish overcame the starting struggle, grew bigger, and now are voracious for anything that comes.
   I can see that if I don't supply smaller food, I will lose majority of the spawn, even though they look active and healthy.
   I remember that back in Europe some 60 years ago when  all these products were not available, we fed fry either yalk from a hard-boiled egg, or gently scraped raw beef, which looked more like blood than pieces of meat. Another source of food was breeding semi-microscopic organisms by leaving a leaf of lettuce (or other material)  in water to partially rot. This is tricky, because if you get a wrong flora, water may spoil quickly or fish be killed.
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I hope that one of you is already using such culture, and I could take a sample and multiply it for my use.  

Being desperate, I tried yesterday raw beef: I put a piece of lean sirloin about 2 cubic cm big into blender with 1/3 cup of water, and processed it for about a minute, then strained it on a dense tea strainer. Resulting pink liquid hardly showed any particles, but when I fed small amounts, all fish got really excited about it. I am hesitant to continue with this though;
1000 fish in a 10 gal tank  where cleaning and water changes are difficult can quickly turn into a disaster.

[Nerine]

Hoping the fish are doing all right!! were you able to find anything else to feed them?

I don't have anything...but I used to feed a gel food from the petstore (not sure if it's available anymore?) and there was a fine powder food..