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Food and Feeding

eggs, males, breeding, fish and feed

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FOOD AND FEEDING.

From the peculiar dental armature of the gaff-topsail (the teeth being confined to villiform bands on the vomer and palatines and to supra-pharyngeal and infra-pharyngeal pads, and hence adapted for crushing rather than biting, tearing, or holding), one would conjecture that it is not a feeder on fishes, a predatory fish in the common acceptance of the term, but rather a bottom feeder. This finds con firmation in the fact that it prefers a muddy or sandy bottom in muddy water where it finds its food by the help of its tactile organs, the bar bels. Moreover, dissections of scores of both males and females make it clear that the gaff-topsail feeds almost exclusively on crustacea. Autopsy reveals an occasional fish (menhaden or croaker), but its principal food is crab, blue crab, eked out with an occasional shrimp. From the much-distended stomachs of sundry specimens, crabs 4 to 5 inches wide have been excised, so large that one wonders how they could have been swallowed. Ocular examination of the contents of the intestines has shown large fragments of the chitinous cover ings of crustacea with here and there a claw. On the whole, these contents present a felt-like appearance which persists under an ordi nary eye-glass. The microscope, however, resolves this material into minute fragments of chitinous shell, grains of sand, bits of dirt so small that they give the Brownian movement, and immense num bers of crustacean hair-like seta. There can be no doubt that crus tacea large and small form the major portion—perhaps as much as nine-tenths—of the food of the gaff-topsail catfish.

The foregoing observations have been made on females and non breeding males. Such have always been found in fine full-fed condi tion, the intestinal tract being plump, well-nourished, fat, distended. Breeding females do not have the distended stomachs of the non breeding ones, the size of their colossal ovaries forbidding this, but all have been found in good condition.

Breeding males, whether carrying eggs or not, may always be recognized at a glance by their depressed hyoid regions, their "double chins." For those without eggs it may be conjectured that they have

through fright or some mishap given up their eggs, or that they have not yet received them but are prepared therefor—in similar fashion as the uterus of the stingray (Dasyatis say) becomes villous to receive the egg even before the latter descends into the oviduct. Such breeding males always have empty, pendulous stomachs and stringy intestines without trace of food in them. This has been found the case in more than a hundred autopsies. From these facts the con clusion is drawn that the ovigerous males of Felichthys felis do not feed at all during the time of gestation. Certain it is that no body of any size can pass down the oesophagus without the eggs following.

Holder (1904), however, speaks of the fish with eggs in their mouths biting ravenously at hooks baited with shrimp. But Evermann and Goldsborough (1902) expressed the opinion that Conorhynchus nelsoni does not feed during gestation. Day (1873) found no trace of food in the intestinal tracts of either Arius or Osteogeniosus, both oral gestators of India. Boake (1866) concludes that the Ceylonese Arius may feed on microscopic "nutritious particles" floating in the water, but Turner (1867), after studying Boake's specimens, thinks that the amount of food obtained in this way would be practically nil. On the other hand, Wyman, though inclined to think that gestating males fasted, from finding in the mouth eggs of another species was led to believe that the fish might have disgorged the eggs in order to feed, and that on taking them up again the eggs of "another species" were also included. The wording of his sentence indicates that the other species was also a catfish. If this be true it may be conjectured that these eggs were the smaller unripe eggs of the female from whose ovary came the other ripe eggs, extruded and taken into the mouth of the male at the same time with the ripe eggs.

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