Fish, Tanks and Ponds


Fish, Tanks and Ponds
A comprehensive guide to fish

Fish Anatomical Terms

Adipose fin, A fatty none erectile fin, between the dorsal and tail. Not present on all fish.

Anal fin, Situated to the rear of the fish on the underside.

Barbel, A sensory organ used to taste things and to feel things, some Corydoras Catfish use them in their courtship.

Bifid spines, Small erectile spines found on some fish, beneath the eyes of some Loaches or on the Caudal Peduncle in Surgeons and Tangs.

Caudal fin, An alternate name for a fishes tail.

Caudal peduncle, The end of the fishes body, where the tail is attached.

Dorsal fin, The fin in the middle of the fishes back, Some fish like Guppies have two, one behind the other.

Genital papilla, The sex cells of both sexes empty into the Genital papilla before leaving the fishes body.

Gonopodium, A modified Anal fin used by male livebearers for copulation.

Gravid Spot, A dark spot above the anal fin on some livebearers, it is particularly prominent when they are about to give birth.

Labyrinth organ, An extra breathing organ similar to a primitive lung which is used to extract Oxygen from the atmosphere.

Lamella, Gill filaments.

Lateral line, A series of pores containing nerve endings that run down both sides of a fishes body.

Mandible, The lower jaw.

Mouth types

  • Inferior: downward facing.
  • Terminal: forward facing.
  • Superior: upward facing.

Nuchal hump, A large lump on the heads of some mature Cichlids.

Operculum, Gill cover.

Ovipositor, The egg tube, this is usually on visible just before and just after spawning.

Pectoral fins, Along with the Pelvic fins these are used mainly to steer the fish.

Pelvic or ventral fins, Paired fins on the underside near the lower chest of the fish, in some fish (Angelfish Gouramis etc,) these fins have become elongated and Gouramis can actually taste things with them.

Rays, Spines that support the fins. There are two types of rays, soft rays and stiff rays. Ray counts are used as a key to identifying different species of fishes. Stiff rays are given roman numbers and soft rays ordinary numbers so a fish with one stiff ray and 15 soft rays in it's anal fin would look like this on an ichtyological paper:

A: I + 15 (14 - 16).

A signifies the anal fin, I = one stiff ray, 15 = the usual number of soft rays and (14 -16) means that the number of soft rays can vary between those numbers.

Scales, Small tough plates covering the fishes body to protect against abrasions etc.

Sclerites, (sklehr-ites) Tiny (usually microscopic) calcium deposits found in soft corals to aid in maintaining the body structure. They form in various shapes and sizes and are used in taxology.

Scutes, Bony plates in the place of scales, sometimes with protective spines.

Swim bladder, A muscular gas filled sac that can be expanded or contracted in order to control buoyancy.

Tropheomata, A feeding organ for unborn fry (genus Jenynsia).

Trophotaenia, A feeding organ for unborn fry (genus Goodeids).

Yolk Sac, Food for non free swimming fry.

Fish Anatomy

Many of the terms used when referring to fish can be confusing at first but knowing them and being familiar with them can help when asking a question, for example if a fish has damaged it's gills in some way it would help to answer the question if the responder knew where the damage was precisely. The Operculum is the gill cover and could be damaged by a trauma of some sort. The Lamella are the gill filaments and could be damaged by ammonia, protozoa and so on. So by being a little more specific is far more helpful than simply saying "damaged gills" and it is likely to to receive more and better help as a result.