Endlers are almost industructable. They are very prolific need proper filtration and water changes. They will likely as a colony out grow the 10 Gal. I tend to feed live or decap brine shrimp daily followed by mostly high protein flake food such as Ken's earthworm, beef heart, chicken liver, black worm and guppy mix. If you have ever tried Ken's Fish flake food you may wish to. You can get 1/4-1/2 poud of those listed above for between $4-$7. $20 bucks and your Endlers can eat until your 110 years old.
Also, unless you want to seriously sell them, don't spend a ton on N-Class. Many advertised as N-Class really are not and the mixed genes from K & P Classes don't impact their not eating fry. With proper food and a little cover all the fry will survive. I currently breed Black Bars, Chillis, Blonds and Yellow Jackets. I have some of most up for grabs all the time.