Yes! Of course it varies seasonally as with all lakes, but the lake is stocked with rainbow trout several times a year. Other fish you can catch at Rainbow Lake are largemouth bass, channel catfish, bluegill, green sunfish and illegally introduced northern pike. Here is a link the Arizona Fish & Game Department website.
You may see some very large fish near the shore of the lake. These are weed eating carp that help control grasses growing in the lake during the warmer months. Please throw them back if you catch one!