105 



They are provided with strong spines in their dorsal and 

 pectoral fins, and an interesting illustration of the advantage 

 of such weapons was observed in the tanks. The " Dik-kops " 

 {Gobius of various species) are abundant, and several are gener- 

 ally present in the tanks of the aquarium, where they thrive 

 very w^ell. They are little fish with rather wide mouths, always 

 on the alert and ready to seize anything likely to be edible. 

 On one occasion a young Barbel, about three inches long, was 

 put into the tank, and immediately began investigating its 

 new surroundings, trailing its long feelers over the bottom ; 

 the new arrival attracted the attention of a large Dik-kop (G. 

 nudiceps), which, after a somewhat prolonged consideration, 

 suddenly made a dash at the stranger and succeeded in seizing 

 it bodily in its large mouth. It as quickly ejected it, however, 

 and rushed about the tank shaking its head violently, evidently 

 much upset, while the small Barbel proceeded unconcernedly 

 with its investigations as if nothing had happened, its strong 

 spines, which can be stiffly erected, no doubt having served 

 it in good stead in this emergency. It was not again inter- 

 fered with. 



Fishermen sometimes get painful wounds by the incautious 

 handling of the fish. Though there does not appear to be any 

 definite poison secreted, the wounded part often becomes 

 inflamed and causes great pain. 



The Harder or Mullet {Mugil capito). 



This fish is well known. Unlike the previous fish, it is more 

 of a pelagic habit. Its laterally placed eyes and elongate form 

 are probably adaptions for such a life. Fishermen observ'e 

 that it has some peculiar habits especially with regard to its 

 movement in shoals 



One peculiarity observed in the case of young Harders in 

 the tanks may be mentioned. They are usually timid fish, 

 and are easily startled by any unusual occurrence or the 

 presence of a Klip-fish. Towards evening, however, in the 

 tank they sometimes showed a rather playful behaviour, and 

 indulged in what appears like a sort of game. After some 

 gambols, or at least rapid spasmodic movements of the shoal, 

 one fish may be observed in an almost vertical position in mid 

 water with head down and tail almost vertical. It keeps up 

 a peculiar quivering of the fins, especially of the caudal. It 

 is soon followed by the others one by one till the whole shoal 

 is grouped together in a small space, each fish behaving in this 

 peculiar manner. Suddenly the fish, as if at some given 

 signal, disperse wildly in various directions, afterwards re- 

 suming their gambols in a shoal. The vertical position is 



[C.P. 6-'i4.] 



