Vinegar eels are a common first food for betta fry and many other fish. They are smaller than most nematodes, last longer in the tank, and swim throughout the water column which prevents too much bottom-feeding. They are extraordinarily easy to keep and can thrive for years with minimal attention. Vinegar eels, in my opinion, are a must-have food for all betta breeders. While other cultures might crash or brine shrimp hatches might fail, you will always be able to pull out vinegar eels and know they are ready to harvest when you need them.