Join Date: Oct 2010
Location: Victoria, Australia
It's likely the diet of your fry that is the problem. You can't raise a spawn on vinegar eels alone. This is a food that breeders tend to use only until the fry are large enough to move onto more nutritious foods such as freshly hatched brine shrimp.
What you need to do (if you don't already have them on hand), is purchase brine shrimp eggs. Look for those that guarantee a high (90%+) hatch rate. There are numerous tutorials and articles online outlining the different methods for hatching and harvesting brine shrimp. Have a read through some of these, and then figure out the method that works best for you (it make take some trial and error).
Daily (or even twice daily) feedings of BBS coupled with frequent water changes should guarantee a faster growth rate in your fry.
The only thing to watch with BBS is that if regularly overfed, it can cause issues with the swim bladder.
Once the fry start to get larger, you can then start to introduce other foods into their diet.