Signs of tropical fish dying due to lack of oxygen

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Signs of tropical fish dying due to lack of oxygen
Giving your fish room to breathe. (Tom Brakefield/Stockbyte/Getty Images)

Tropical fish come in two varieties: those that live in saltwater and those that live in freshwater. Tropical fish that inhabit saltwater tend to be darkly pigmented. Freshwater tropical fish, however, are generally brightly coloured. For this reason the latter make attractive pets in aquarium-based environments. It is important that an aquarium is well maintained. This includes ensuring that the fish have sufficient oxygen. Low levels of oxygen can cause distress and death to tropical fish.

Oxygen and water

Contrary to popular belief, fish do not breathe water. Just like people, fish breathe oxygen. Whereas humans have lungs, fish have gills. The gills of a tropical fish are found on each side of the pharynx, a component of the respiratory system. A tropical fish breathes by taking in water via its mouth, then distributing it to the gills. The primary purpose of the gills is to utilise dissolved oxygen from the water and get rid of carbon dioxide. If water-based oxygen levels are low, however, this can prove fatal for tropical fish.

Signs of tropical fish dying due to lack of oxygen
The gills of a tropical fish. (Stephen Chernin/Getty Images News/Getty Images)

Levels of oxygen

It is very important that oxygen levels in an aquarium meet the needs of tropical fish. One of the most important components of any aquarium is the filter. It performs a number of functions. The filter is designed to remove from the tank waste materials excreted by the fish. The filter will also get rid of decaying and dead vegetation, algae and rotted food. Algae, if left unchecked, can grow wildly. Large amounts of algae can quickly deplete an aquarium of oxygen. This can have a detrimental effect on the health of tropical fish.

Signs of tropical fish dying due to lack of oxygen
Algae can be a problem. (Comstock Images/Comstock/Getty Images)

The symptoms of hypoxia

A lack of oxygen in tropical fish is known as hypoxia. There are a number of symptoms to look for when it comes to diagnosing hypoxia. If the fish are spending more and more time near the surface of the water, that is a major warning sign. When oxygen is depleted from an aquarium, it is the higher levels of water that lose their oxygen last. So, tropical fish will gravitate to the top of the tank in an attempt to breathe easier. Over-breathing, and gills that are noticeably widened and appear inflamed, are signs of oxygen deficiency in fish, as is a loss of the body's normal bright colouring.

Signs of tropical fish dying due to lack of oxygen
Warning signs of low oxygen. (Medioimages/Photodisc/Valueline/Getty Images)

Resolving the oxygen problem

It is important that when hypoxia is evident in tropical fish steps are quickly taken to rectify the situation. Removing around 50 percent of the old water and replacing it with new, oxygen-rich water is a good place to start. Oxygenating tablets, which dissolve when placed in water and that release oxygen, can help significantly, too. They are widely available at pet-shops. Ensure that the filter is in full working order. Remove any and all build up of oxygen-depleting algae. Over-crowding may be an issue, too. Too many tropical fish, in an inadequately-sized tank, can quickly lower oxygen levels.

Signs of tropical fish dying due to lack of oxygen
Filters and oxygenating tablets. (Comstock Images/Comstock/Getty Images)

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