I would be more worried about it if it was late Fall instead of in the Spring. You will have a LOT of BG spawning soon and they will replenish the population shortly.

Personally I really don't worry about overflow causing a problem. If I was really worried about it, I'd call in a company to elextroshock the pond to do a population survey and then adjust the remaining fish population based on the electroshock survey results.

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).