Several types of hatchet fish form another little group of very popular fishes. The main apparent difference between them is their coloration, otherwise they require much the same in terms of care and feeding are surface-feeders and dwellers. They can rise progressively above the surface in much the same way as a hydrofoil and often skim over the surface of the water for up to 2m (6.5ft). This is because they have developed long pectoral fins that they can 'beat' like wings. Be sure to attach a very tightly fitting cover over any tank containing hatchet fishes. The most commonly seen species in the aquarium hobby is the silver hatchet fish (Gastropod stencil). It grows to about 6.5cm (2.6in) and thrives in soft, slightly acidic water Bata temperature of about 26°C (79°F).The three-lined pencil fish (Monotonous trifocals) is a small, very peaceful fish from South America that grows to about (2in). The body shape is very long and slim, with a pointed snout and tiny mouth. The water should be kept at about 26°C (79°F) and he soft and very slightly acidic. The fish enjoys live foods, but it will eat frozen, as well as freeze-dried and flake food. Small tetras, linebackers Cordovans catfishes are ideal partners for this pencil fish.
