Fisheries and Aquaculture Journal
Open Access

A Note on Fish Disease and Parasites

Armitage Ariyati^{* *}Correspondence: Armitage Ariyati, Department of Aquaculture and Fisheries Management, University of Guilan, Rasht, Iran, Email:

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Description

In nearly every body of water around the world, the most abundant vertebrate is a fish. From the deepest parts of the ocean to high alpine streams, fishes live and reproduce. Sometimes in places where no other vertebrates can survive. Whether peering out from a submarine while conducting deep sea research, or stopping for a drink of water during a hike in the mountains, explorers, scientists and naturalists find fishes.

With well over 30,000 species, fishes account for more than half of the total extent vertebrate diversity on earth in other words, there are more living species of fishes than of amphibians, turtles, lizards, birds and mammals combined. Not only are fishes diverse in number of their species, but they are diverse in the habitats in which they live, the foods that they eat, the ways in which they reproduce, communicate and interact with their environment and the behaviors that they exhibit. Fishes can also be extremely abundant the most abundant vertebrates on the planet are the small bristle mouth fishes that are common throughout the vast open ocean. In some cases abundant fishes such as cods, tunas, salmons, herrings and support massive fisheries that feed hundreds of millions of people. By supporting coastal communities and societies, these hundreds have helped shape human history, becoming the foundation for coastal and an engine for global exploration and expansion. Humans use the term fish to refer to several groups of vertebrates that do not have a clear set of diagnostic characteristics unique to them. Fishes is not a monophyletic group because the tetrapods which share a common vertebrate that is not a tetrapod.

Fishes live in water obtain oxygen through gills are ectothermic and have limbs in the form of fins. Naturally, there are exceptions to each of these rules. Some fishes spend time out of the water, some breathe air, some are endothermic and some have no limbs at all. While there is no clear set of characteristics that distinguishes all fishes from all other vertebrates there are four groups that collectively make up the fishes.

The extant fishes include the jawless fishes, the cartilaginous fishes, the ray finned fishes and a small portion of the lobe finned fishes. Of the extant fishes, the ray-finned fishes are by far the most speciose, accounting for more than 30,000 species, the Cartilagenous fishes, the ray-finned fishes, and a small portion of the lobe-finned fishes. Of the extant fishes, the ray finned fishes are by far the most speciose, accounting for more than 30,000 species the cartilaginous fishes include about 1200 species and the jawless fishes include fewer than 100 species. Only 8 species of lobe-finned fishes two species of coelocanths and six species of lungfishes are considered by most to be fishes while the remaining 28000 or more sarcopterigian species are tetrapods. Ichthyologists have been interested in the evolutionary history of fishes for hundreds of years and classification systems have attempted to capture that history in a hierarchical system of names. It remains difficult to implement a truly monophyletic classification, one that recognizes only monophyletic groups, for any large group such as fishes given both the complexity of the tree of life and our continuing uncertainity as to its form.