Shedia CBay Watershed

From the Blog

How Fish Is an Integral Part of the Environment

Fish form a major component of all aquatic ecosystems. They are both prey and predators, providing food for other animals and preying on and regulating numbers of smaller organisms. They are thus essential components of food webs in freshwater, brackish and marine environments.

If There Were No Fish

The absence of fish can lead to an imbalance in the food web and in ecosystems. This can result in nuisance organisms, such as mosquitoes becoming overly abundant. Fish predation on mosquitoes is very important since mosquitoes transmit many dangerous diseases.

A drop in fish numbers can have huge conservation implications especially for predators that rely heavily on them for food. For example, the bald eagle population numbers decreased dramatically when the sockeye salmon population collapsed in Glacier National Park in Montana.

Fish are hugely important as food for other animals, particularly in the ocean where various mammal and bird species prey on them. Fish are also very important as suppliers of nutrients in marine systems. They are the biggest source of nutrient replenishment on which all life in the ocean depends. Fish excretion alone provides many nutrients for algae and other organisms such as sea grass.

Different Species

Species of fish are important in mineralizing such nutrients as phosphorous and nitrogen, and through their activity they can change bottom sediments of their habitat. By disturbing the sediment, they also disturb microscopic and macroscopic organisms living in the sediment. These organisms then become available for other organisms to feed on.

Some fish feed on vegetation which helps to reduce the growth of weeds and vegetation in water such that a water body does not become overgrown with vegetation. Grass carp has been introduced into some countries for this purpose. Unfortunately, since grass carp are not native in these countries, they themselves have become a pest.

Certain species of fish can be used as biological indicators for habitat quality. This means that their abundance and changes in abundance or density over time can indicate if a habitat has experienced physical disturbance or pollution. This can then lead to planning efforts by conservationists to remediate the environment.


Since fish are such a large component of ecosystems their tissues can be tested for pollution levels as well. Toxic substances entering the water will bioaccumulate at each stage in the food web. This means that fish tissues will be able to show what pollutants are present and at what levels.

Fish are important for both recreational fishing and commercial fishing. Of course, many people rely on fish as part of a healthy diet, which means that we need to ensure our fish populations are healthy and sustainable. Fish provide healthy protein and omega 3 fatty acids as part of a diet. Fish are also used to make other products that people use, for instance, glue.

Fish are such an essential part of our environment that we do have to be concerned when fish population numbers decline. Even if you do not eat fish, they still influence the overall health of our aquatic ecosystems, our rivers, lakes and oceans.