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Diving at Sand Bottom Cave, French Reef, upper Florida Keys, I saw 3 sharpnose puffers.  The largest one was keeping the mid-size one away from the smallest one.  The smallest one had "normal" coloration but the 2 bigger puffers were mottled.  Were these males trying to spawn with the smallest one?  The activity was always centered around the smallest puffer and followed it wherever "she" swam.