Fishy Bits

by Kevin Thurston
From CAS Newsletter and Aquarist, Colorado Aquarium Society
Aquarticles.com

· Mormyrids, which include the popular elephant nose and baby whale have highest brain to body weight ration of fishes. This is probably related to their electrical sense and processing the information contained in their electrical field.

· On the subject of electrical discharge, fish are the only class of animal capable discharging electricity into their environment.

· If a fish is depressed, it isn't sad. It means that its body is flat like a flounder. If it is compressed, it is flattened from side to side like an angel fish.

· Cichlids are not the only fish that are mouthbrooders. Other mouthbrooders include some Anabantoids (Gouramis and Bettas), some catfish and Arowanas.

· The genus name Synodontis means fused tooth plates. Notice the similarities between the syllables in this word to the English words synergism and dentist.

· The genus name for swordtails is Xiphophorus, which means sword carrier. Notice the similarity to the genus name of the marine swordfish Xiphias.

· When the swordfish, Xiphias gladius, is first hatched it has a long beak like mouth. As it matures, the lower jaw recedes as do the teeth in the upper jaw, leaving the long sword-like structure.

· When commercially farmed catfish and trout were tested for the biochemical processes for digesting lactase, the sugar contained in milk, the tests were positive. This allowed the inclusion of dairy by-products in commercial feeds. It is strange that fish can digest dairy products when amphibians, reptiles and birds can't. It is an evolutionary puzzle.

· When an investigation into the cause of death of a fish is done it is called a necropsy, not an autopsy.

· The archer fish is not the only fish capable of squirting water. I have had a long-nose butterfly fish squirt water at me at feeding time. The water stream was too weak to cover much distance. On the other hand I have also been shot in the forehead by an archer fish and I can tell you that it is a very powerful shot.

· Strangely enough the long-finned or veil characteristic of angel fish is dominant. This means that if you cross a long-finned angel with a normal finned angel you will get either 50% or 25% of the offspring with long fins, depending on if the long-finned parent is homozygous or heterozygous. Homozygous means that both chromosomes that carry the genes for fin length have the long fin gene. Heterozygous means that one chromosome carries the long fin gene while the other carries the normal fin gene.

· Many catfish, including the popular Corydoras spp., are able to utilize atmospheric oxygen to supplement their normal breathing.