Stickleback

a family of small, active, greedy, quarrelsome fishes. The name is derived from two, four, or ten sharp spines, according to the species, that take the place of the dorsal fin. Gray, black, or olivaceous, they are found in brackish waters. The common two-spined stickleback is about seven inches long. It is worthless for food. The stickleback is noteworthy for its nest. The abdomen of the male is provided with a large gland from which it is capable of exuding a clear, stringy secretion that coagulates into threads in the water. With the aid sometimes of grass or bits of weed, it winds these threads around a central cavity until it has formed a nest comparable to a lady's muff lying on its side. In this nest, the female places the eggs. The male remains on guard to defend both eggs and young until the latter are sufficiently mature to make off and take care of themselves. The stickleback is an interesting fish in an aquarium.