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Alternate male strategies which allow small males to engage in cuckoldry can develop in species where spawning is dominated by large and aggressive males. Cuckoldry is a variant of polyandry, and can occur with sneak spawners (sometimes called streak spawners). A sneak spawner is a male that rushes in to join the spawning rush of a spawning pair.[13] A spawning rush occurs when a fish makes a burst of speed, usually on a near vertical incline, releasing gametes at the apex, followed by a rapid return to the lake or sea floor or fish aggregation.[14] Sneaking males do not take part in courtship. In salmon and trout, for example, jack males are common. These are small silvery males that migrate upstream along with the standard, large, hook-nosed males and that spawn by sneaking into redds to release sperm simultaneously with a mated pair. This behaviour is an evolutionarily stable strategy for reproduction, because it is favoured by natural selection just like the "standard" strategy of large males.[15]

Cuckoldry occurs in many fish species, including dragonets, parrotfishes and wrasses on tropical reefs and the bluegill sunfish in fresh water. Sneaker males that becomes too large to hide effectively become satellite males. With bluegill sunfish, satellite males mimic the behaviour and colouration of the females. They hover over a nest containing a pair of courting sunfish, and gradually descend to reach the pair just as they spawn. "Both sneaker and satellite males are usually badly chewed up by irate parental males by the end of the spawning season, but their strategy is nevertheless a successful one (giving them high fitness). Because these smaller males do not have to spend any energy on parental care, they can spawn at a much younger age than the parental males. Parental males may be 6 or 7 years old before they are large enough to compete successfully for the best nest sites, but the sneaker and satellite males may be only 2 or 3 years old."[4]:161–2[16]