No idea what happened. The all looked fine up till the second I would find them dead. The endler in the tank with them is still fine, the three ottos and so are the frogs. Water tested fine but I still did daily 20 percent water changes.

Added my betta to the tank and shut down the 5 gallon.

May add one more frog and a couple more endlers if the betta keeps ignoring the one I have.