18-24 inches is the sign of a good planktonic base. 53 indicates a shortage. Phytoplankton are microscopic plants that are fed on by zoo plankton that are fed on by tiny "bugs". They are groceries for larger bugs that feed tiny fish and so on up the food chain. 53 inches indicates a shortage of the basis for pond life.

Since I don't know Indiana ecosystems, I will let others advise.

It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.

Without a sense of urgency, Nothing ever gets done.

Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP