Fish Nutrition

There are thought to be over 33,000  different species of fish in the world, and around 10,000 in the ornamental fish trade. With feeding strategies and nutritional needs varying between fish families and even species. Whilst this may sound daunting, it is easy to provide good nutrition by following some basic principles.

Freshwater and marine ornamental fish can differ in their nutritional & feeding requirements. For example: some fish have evolved to feed on specific types of foods, with fish having different feeding strategies, such as herbivores, carnivores and omnivores. With fish in their wild habitats obtaining their nutritional needs through a variety of both plant and animal sources. However, the majority of aquarium fish are omnivores and eat both plants and animals. It’s important to ensure that the food fed is nutritionally balanced and complete meeting the requirements of the type of fish.  

Fish also have particular physical feeding needs.  They can be bottom, middle or surface feeders or algae grazers and the diet offered needs to be appropriate to meet these different needs. Unless there is only one species of fish in the tank, it is very likely that different foods will be needed: some floating, some sinking, and targeted to feeding strategy of the fish  Owners will need to take this into consideration when choosing their fish and benefit from some guidance from the retailer.

The diet offered, needs to be appropriate to meet these different needs. In other words, it should deliver an appropriate amount of different nutrients, and be in a format that the fish can easily eat and digest. A good quality prepared food will provide fish with a balanced diet. This will include nutrients such as protein (which supplies the 10 essential amino acids that most fish require), fats (for energy and as a source of essential unsaturated fatty acids), vitamins and minerals. Some fish foods contain pigment enhancers, to bring out the natural colours of the fish (e.g., in the form of ingredients such as shrimp meal, Spirulina algae, and the carotenoid astaxanthin). 

Most species of fish are unable to make their own Vitamin C and so must be provided with this nutrient in the diet. Essential Vitamins including A, C, D, E, K and B group should be supplied in all complete fish foods. 

• Generally, fish should be fed two to three times daily. Fish will learn the routine and equate you being close to the tank as food time! 
• A few flakes, granules or pellets per fish is sufficient. The fish should eat all the food in two minutes or less.
• Err on the side of caution - over feeding is much more common than under feeding. 'Over feeding results in incomplete digestion of food, which can lead to increased waste products excreted by the fish. This combined with uneaten food can then pollute the water.
• It is important to ask about the specific feeding needs of a fish before purchasing it, as some may have special requirements. 

Fish food quality has a significant impact on the aquarium or pond environment, and how easy it is to maintain. This is because it is the main source of the dissolved and solid waste that fish produce. Overfeeding, or feeding a poor-quality food, will result in greater waste production, and faster pollution of the water. This in turn necessitates more maintenance to keep the environment healthy. 

Good quality foods use the right ingredients, manufacturing processes, and formulas to keep waste production to a minimum, whilst at the same time providing the fish with a healthy diet. 

“Nutrition problems usually result from feeding the wrong type of food or feeding improper amounts (too much or too little) so follow the principles above for healthy, happy fish.” Nicole Paley, UK Pet Food

If you go away on holiday, ask a responsible person to check on the fish and equipment each day. Remember: 

• Tropical fish will need checking daily . 

• Leave instructions on how to feed and avoid overfeeding. 

• Prepare some meals in advance, which are of the correct ration size. 

• An automatic feeder will release a measured amount of food each day. This still needs to be checked every day to ensure it’s working correctly. 

Remember it's actually better to underfeed rather than overfeed because fish are more susceptible to poor water quality than a lack of food.