Top 10 Prehistoric Fish Alive Today

This list looks at fish that were around in remote, prehistoric times and have survived to our time, still keeping their “prehistoric” looks to prove it. Feel free to mention those I have excluded in the comments.

10. Hagfish

According to the fossil record, hagfish have existed for over 300 million years, which means they were already old when dinosaurs took over the world! Found in relatively deep waters, these animals are sometimes called slime eels, but they are not really eels, and actually, they may not even be fish at all, according to some scientists. They are very bizarre animals in all regards; they have a skull but lack a spine, and they have two brains. Almost blind, they feed at night on the carcasses of large animals (fish, cetaceans etc) which fall to the sea bottom. They owe their “slime eel” nickname to the fact that they produce a slimey substance to damage the gills of predatory fish; as a result, they have virtually no natural enemies.

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Freshwater Fish Disease

Typically, fish diseases are caused by pathogens (agents that cause disease) as follows:

a) Parasites (Endoparasit / exto-parasite)
b) Fungi
c) bacteria
d) Virus
e) Causes such as genetic and environmental factors

i) Primary Disease

These disease usually occurs when fishes react with each other pathogens for the first time. This happens when we add large fishes together with small fishes. Even though large fishes were infected with pathogens, it will not show any signs of disease because most large fishes have the immunity against the disease. Unfortunately for these small fishes, it is easily attacked by diseases. In the mating process, primary disease could also occur where the pathogen can spread from female to its young.


ii) Secondary disease

Occurs because of stress factors. This can weaken the fish and cause the fish to easily attacked by pathogens. Factors such as temperature, water quality and others, could easily weaken the fishes and they would not be strong enough to fight the pathogen attack.

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