THE COWFISH

Acanthostracion polygonius

This unusual reef fish has an armor of heavy hexagonal scales covering much of its body, and an elongated caudal peduncle (tail stem) with rounded fins. It has a small, puckered mouth and tiny ‘horns’ over its eyes, with a sloped face and pronounced forehead, giving it its bovine name.
Order – Tetraodontiformes
Family – Ostraciidae
Genus – Acanthostracion
Species – polygonius

Common Names:
Common names in the English language cowfish and trunkfish. Other common names include baiacu-de-chifre (Portuguese), botelia (Spanish), coffre polygone (French), cofre (Spanish), peixe-cofre (Portuguese), peixe-vaca (Portuguese), torito (Spanish), torito hexagonal (Spanish), and torito panal (Spanish).

Habitat:
The cowfish live in the clear waters of coral reef habitats at depths of 10-262 feet (3-80 m).

Distinctive Features:
The triangular body is nearly enclosed in a “carapace” consisting of thickened hexagonal scale plates that are firmly attached to each other with the exception of the cheeks to allow for respiration movements. There are openings in the carapace for the mouth, eyes, gills, fins, and the flexible caudal peduncle.
There is one pair of scales in front of the eyes. The terminal mouth is small with fleshy lips and the gill openings are short with slits located in front of the bases of the pectoral fins. There are no pelvic fins and the caudal fin is distinctly rounded.

Dentition:
The teeth of the cowfish are moderate and conical in shape with usually less than 15 teeth in each jaw.

Size, Age, and Growth:
The maximum length of the cowfish is 19.7 inches (50.0 cm) total length (TL), although it more commonly reaches lengths of 9.8 inches (25.0 cm) TL.

Food Habits
The honeycomb cowfish feeds on marine invertebrates including shrimp, tunicates, and sponges.

Reproduction:
Very little is known about reproduction within the family Ostraciidae. However, it has been observed that this species forms social harems consisting of one male along with only two females.

Predators:
Larger fish are potential predators of the cowfish, however it may be undesirable as a prey item due to its protective external armor, the carapace.

Parasites:
Three monogeneans parasites have been reported from the cowfish: Haliotrema minutum, H. torridum and H. kritskyi nom. nov.

You can get the cowfish and many more marine fish at Kenya Marine Center.

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EXAMINATION OF DISEASES IN MARINE FISH

Most of the tropical fish in domestic aquariums up to almost 99% of them are wildly caught and transported to the retailers and wholesalers within 24-48 hours.

Removing fish suddenly from their natural habitat exposes them to stress from which some of them die. Moreover, during transportation some marine fish those that survive could have diseases and pass the same to the fish already in the aquariums.

Adaptation tom the new environment could be a bit problematic and so their defense mechanism is often weakened to an extent that they are more susceptible to diseases. This is why the quarantine tank are very important.

Using a microscope, the skin and gill smears or fins and gill parts are examined in seawater on slides. In seawater, the structure of cells, bacteria and parasites remain intact while they can be damaged in freshwater. However, freshwater can be used to examine internal organs.

Many large-scale symptoms of diseases are very similar and can easily lead to mistaken choice of drug treatment, with possibly harmful consequences.

Microscopic review of the diseases gives one a clear concept of the disease.

Materials:

  1. Two dissecting needles
  2. One small and one large pair of scissors
  3. One scapel with replaceable blades
  4. One sharp and one blunt pincer
  5. Eye-dropper containing aquarium water

How to kill fish:

The fastest and the surest way to kill fish to cut deeply into its neck with a knife or scissors.


To detect pathogens on skin or skill, carefully scrap the mucus layer with a scalpel and place it into aquarium water on a slide then cover with the cover slip.

Afterwards, the gill cover can be cut away to expose the gill. Some gill tissue can be removed with the scissors or pincers, placed into a drop of seawater on a slide, and covered by a cover slip.

If necessary, the fish can be dissected:

  • Cut the stomach open, with scissors, from anus to gills without damaging the internal organs.
  • Beginning with the anus, open up the side of the fish to the edge of the gill cover.
  • After removing cut skin, the internal organs are exposed for examination.

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