Spawn Rearing Kit: Requires a one gallon wide-mouth jar, which isnotincluded. If you are having trouble getting spawns to free-swim properly, you may want to give one of these a try. There are people using these not only for angelfish, but for pleco eggs, eggs from mouthbrooders and other aquarium fish.
Tip: Cut a small slit in the top foam piece and inserted a short 3" section of 1/2" PVC to use as a feeding hole or an easy place to add the wigglers or small snails after the fry free-swim. Just make sure the pipe sticks out above the water line.
One Gallon Wide-mouth Glass Jar: The Spawn Rearing Kit is not included. These jars have many uses in a fish-room. They are used for our Spawn Rearing Kit. We also have two jars on hand for every spawn we hatch where we're not using the Spawn Rearing Kit. One to hatch the spawn in and one to age water for 24 hours. We then use this aged water to change water on the jar with the slate. Many aquarists use glass jars to hatch their brine shrimp eggs and to culture things like micro-worms, infusoria or vinegar eels. We use dozens of these on a daily basis.