Very tiny! Just over 0.5 cm long. Caught in a small permanent pool about 50 feet from the ocean. The pool was about 1-6 inches deep, and full of dense, fluffy green algae. Mummichogs, killifish, and shrimp were also in the pond. Unfortunately, I wasn't able to examine the spines on this fish for fear of injuring it. It was released safely, and hopefully I can recapture it when it gets a bit larger.