12 THREE-SPINED STICKLEBACK. 



generally of a small size, the Sticklebacks yield to none in point of interest. There are four 

 well-marked British species, namely, the G. aculeatus (three-spined), G. spiniilosus (four-spined), 

 G. pungitius (ten-spined), and the G. brachycentrus (short-spined) ; the other so-called species, as 

 the G. gvmnurus (smooth-tailed), G. semiarmatus (half-armed), and G. trachurus (rough-tailed), 

 are probably merely varieties of the G. aculeatus. 



Our commonest species, the Three-spined Stickleback, is generally an inhabitant of fresh 

 water, and is to be found in ditches, shallow streams, ponds, and canals, but it also occurs 

 in salt and brackish water. If a specimen be suddenly transferred from a fresh-water aquarium 

 to a salt one, this little fish does not seem the least affected by the change, except that it 

 does not quite accommodate itself all at once to the greater buoyancy of the salt water. 

 According to Nilsson these fish are caught in incredible numbers in the Baltic about the 

 middle of November, when they assemble on the coasts of that sea, and are taken by fishermen 

 in boat loads. They are boiled, and the oil they contain is skimmed off the water: a bushel 

 of fish is said to yield two gallons of oil. The refuse is spread over the ground for manure. 



The food of the Stickleback consists of small worms, larvae, and the small Crustacea, as 

 the Cyclops, cypris, and daphnia among the Entomostraca, and the young of the fresh-water 

 shrimps (Gammarus pulcxj, and water wood-lice (Ascllus aquaticus); but so voracious and bold 

 is this little fish that it will attack almost any living thing. Thompson mentions that a small 

 party of G. spinulosus, the Four-spined Stickleback, was observed near Belfast in the act of 

 killing a horseleech, whose head they immediately devoured. I remember some years ago 

 keeping a small Pike in the same vessel with a number of Sticklebacks, and I shall never 

 forget the persistence with which first one and then another of these fish attacked the Pike's 

 tail. Occasionally the larger fish would retaliate and try to swallow one of its tormentors, 

 but the sauce piquant of those formidable spines always proved too potent. After a few violent 

 shakings of the head, the Stickleback was forcibly ejected from the cavernous jaws of its 

 would-be devourer. The result of these repeated attacks on the Pike's tail was a gradual 

 diminution of that organ, and I, feeling sorry for the victim of these cowardly attacks on the 

 rear, took him out of the aquarium and turned him into a pool of water. Sticklebacks are 

 very injurious to the eggs and fry of other fish, and must therefore be carefully excluded 

 from Trout preserves ; it is, however, no easy matter to get rid of these little pests when 

 they have once established themselves in a fish-pond. Perhaps the most curious and interesting 

 point in the natural history of these fish is their habit of making a nest and watching over 

 the eggs and young fry. The season for observing this habit is in the month of May. The 

 nest is composed of decayed fibres of aquatic plants, and matted together into a mass more 

 or less round, and placed at the bottom of the water partly covered by the mud or sand; 

 three or four circular holes are to be seen at the top of the nest ; the eggs are an aggregated 

 mass of a brown colour, and of the size of small shot. Until pointed out, a Stickleback's 

 nest is a difficult prize to discover, but when once the form has been well impressed on the 

 eye, detection of any number of nests is an easy task. The male fish alone protects the nest ; 

 if it were not for his fatherly care, I suspect that the race of Sticklebacks would in time 

 become extinct, the ova and young fry falling easy prey to the other members of the family. 



Some years ago I had an opportunity of observing how necessary for the protection of 

 a young Stickleback family is the presence of the male parent. I noticed a brilliant fish 

 hovering over his nest, and fanning the water incessantly with his fins. Having captured 

 him, I placed him with one or two others into my collecting bottle. Here I kept him for 

 about half an hour, whilst I amused myself by watching the manners and customs of the 

 fish in their natural haunts. My eye was soon arrested by the spectacle of a large crowd 

 of hungry marauders in the shape of other Sticklebacks of all ages and both sexes that had 

 gathered around the nest of the very parent whom I had a prisoner in my bottle. They 

 rushed at the nest like terriers at a badger, and began to pull it in pieces, knowing there 



