148 FEESH-WATEE AQUAEIA. 



spine each, but no other rays. The anal fin is opposite the 

 dorsal fin, and is about the same shape and size. The caudal 

 fin is slightly convex. The male fish lose their brOliant colours 

 when the breeding season is over. The general colour of 

 Sticklebacks varies greatly according to the condition of the 

 water in which they live. I have found specimens of them 

 almost black. The Three-spined Stickleback is from 2in. to 

 Sin. long. 



The Ten-spined Stickleback, or Nine-spined Stickleback 

 {Gasterosteus pungitius) (Fig. 104) is one of the smallest of 

 British fishes, hardly ever exceeding 2in. in length. It is often 

 found in brackish water, and will live in either a fresh or 

 a salt-water aquarium. This fish also builds a nest, but affixes 

 it to aquatic plants rather than building it upon the gravel 





Fig. 10*. Ten-spined Stickleback (Gasterosteus PUNeiTins). 



at the bottom of the water. The nest in shape is very like 

 a barrel, and is about lin. long. The male fish during the 

 breeding season, instead of becoming crimson, golden, and 

 green, assumes a " velvety -black." The habits and character 

 of the Nine-spined Stickleback are very hke those of the 

 Three-spined. The fish has nine spines in front of the dorsal 

 fin : I have never found one with ten spines. The spines are 

 small and fine. It is not so stoutly b\dlt as the Three-spined 

 Stickleback, nor is its body protected by plates, but is quite 

 smooth. The fleshy part of the tail is very slender. The 

 ventral fins each consist of one bony spine and no other rays. 

 The caudal fin is slightly convex. 



The Common or Yellow Trout {Salmo fario) is a very 

 beautiful and popular fish, and one that will live in an 

 aquarium. The tank in which it is kept should be of rather 



