Cyprinodon macularius

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• William E. Fackert Ill Robert Fargher Some Observations on James J. Gasior Cyprinodon macularius Jaap-Jan de Greet
• Some Observations on Cyprinodon macularius Allan L. Semeit 179

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• 1963, at midday when the water temperature at Manahawkin's middle impoundment was 77 F (25 C), males of F. heteroclitus were driving their females into shallow water choked with spartina roots and spawning in these dense mats. No C. variegatus were in evidence. Three days later only a few F. heteroclitus were present, but not spawn- ing, and the area was filled with C. variegatus. The males were holding territories over the fine white sand which had m o s t of the algae and silt cleared away, apparently by the males. Each male's territory was about 1 to 2 feet (30 to 60 em) in diameter and usually had a clump of algae or a rock included about which the male appeared to maintain his sta- tion. No pit making activity was noted; however, Raney et al. (1953) did not observe pit making by C. variegatus in the tributary channel at Alva, Florida, either. He did note pit making by C. variegatus in the lagoon at Everglades, Florida. More observations are needed on this point. Each male made short straight-line dashes to the edge of his terri- tory which was usually somewhat circular in shape. When another male entered a territory he was met by a head-on charge by the owner and the intruder darted away, although some fin display was noted between larger males. When a female was met she usually began a foraging action. The author's first impression was that she was con- suming eggs left by previous females. The male would come alongside and the two fish would form an S-shape, as seen from above, with the male's head away from the female. This action was identical to that de- scribed by Raney et al. (1953) and very similar to the spawning activity of Nothobranchius species except that the male did not wrap his dorsal fin over the female. After contact there was a sharp separating, called jerking by Barlow (1961) in his studies on Cyprinodon macularius from the Salton Sea of California, and this probably resulted in the release and fertilization of one egg. The female usually swam on right after this or was chased away with vigor by the male, although several spawnings by the same pair were noted, always occurring in rapid succession. This behavioral pattern was nearly identical to that de- scribed by Raney et al. (1953). Any F. heteroclitus, especially groups of them, were immediately charged and they always moved on. Surface swimming Menidia species did not usually gain the attention of the ter- ritorial male C. variegatus. The 50-gallon aquarium in the laboratory was filled with many C. variegatus and five F. heteroclitus. There were no interspecific con- flicts until the time when about 20 F. heteroclitus were added while their aquarium was being cleaned. Immediately the attacks began and continued for two days. The F. heteroclitus tried to hide in the corners of the aquarium and only here could they attempt a defense against the piranha-like attacks of the C. variegatus. It was quite a sight to

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