The Fish Vet's Blog

It is best to pour a measured amount of food into the lid of the food container and then adding this to the tank. Do not use wet fingers to retrieve food from the container as the moisture from your wet hands can cause deterioration of the food.

Where do my fish eat?

Surface feeders will tend to have “superior” mouths. These are up-turned and looks a bit like a frown. Examples of these include the danios, white clouds, butterfly fish and hatchet fish. Those with down-turned mouths are termed “inferior”. Not surprisingly, these fish feed off the bottom. Some examples include various catfishes and loaches. Fishes with “terminal” mouths tend to be more versatile and can accept feed throughout the water column.

Varieties of fish feed to suit different dietary and feeding habits of fishes

Today we are able to keep many different species of fish from various regions all around the world. The world being a vast and ecologically diverse sphere means fish species from different areas will have different dietary patterns, habits and requirements. Within regions you will also have predominantly carnivorous or herbivorous, and preferential bottom, middle and surface feeders. Luckily with today’s scientific knowledge and technology we have many varieties of fish feed to suit almost any species, ranging from pre-formed dried foods to fresh live foods. The food in which you feed to your fish should be as close to or as similar to the foods they would normally consume in their natural habitat to keep them in optimum health. Fish should also be fed with a variety of foods (i.e. dried, frozen, live) to ensure all nutritional requirements are being met, and to provide them with different stimulating flavours and textures.
Varieties of food include:
– Dried Foods: These come in the form of flakes, pellets, granules, sticks, tablets and wafers. Depending on the species you are targeting to feed, these foods can be designed to float at the top for surface feeders, sink slowly through the water column for mid-water feeders, or sink quickly to the floor for bottom feeders.

– Frozen Foods: These are usually presented as frozen into cubes in blister packs or solid blocks in resealable bags for convenience and are available from the freezer section of your local fish shop. Common components include bloodworm, brine shrimp, mysis shrimp, daphnia, tubifex worms, squid, vegetable meals and mosquito larvae. A good quality frozen food should be free from parasites, harmful bacteria and odours, and also have retained nutritional and sensorial value.

– Live Foods: The most commonly available live foods sold in fish shops include blackworm, brine shrimp, earthworms, crickets, meal worms, vinegar eels, microworms and feeder fish. Fishes are most eager to eat live foods, however, beware that some of these foods may introduce diseases to your tank.

Storage to maintain optimum quality

In order for feed to be in an acceptable state when fed to fish, appropriate measures and practices must be undertaken. Incorrect storage can result in loss of nutritional value, mould growth, fat rancidity and infestation by insects and rodents. During storage, it is inevitable that the vitamins in formulated foods will degrade with time. Vitamins are highly reactive and unstable organic compounds that can be easily denatured by oxygen, heat, moisture and ultraviolet light. The rate of the loss depends largely on the vitamin and the conditions in which the food is stored. Thus dried foods should be stored away from direct sunlight in a sealed, airtight container. The conditions under which it should be stored should be cool, dry and exempt from rapid changes in temperature.

During manufacture certain measures are taken to eliminate bacteria and moulds including heat and dehydration steps, but there are certain spores of moulds that are able to survive the harshest of treatments (Soyaqua, 2008). These spores are able to become active only when favourable conditions arise, such as sufficient moisture levels and temperature. These spores grow best when the moisture content of the feed is 14.5 to 20% combined with a relative humidity of 70 to 90% (Soyaqua, 2008). Therefore moisture must not be introduced to dried foods through actions such as letting water droplets enter the container during feeding or leaving the container open for unnecessarily long periods of time.
Fish feed is generally quite high in levels of unsaturated fatty acids as they are essential for good health and growth of many fish species. Though beneficial, it renders the feed highly prone to oxidative rancidity resulting in ‘off’ odours and flavours, and so must again be stored away from direct sunlight, as this can speed up the oxidative process.
Frozen foods should be stored at a steady temperature of approximately -18^oc with minimum fluctuations. These foods should not be defrosted and refrozen repeatedly as it will degrade the food value.
Live foods can be kept in the refrigerator to slow biochemical reactions, prolonging the time in which they can be kept.

Introduction

Ornamental fish keeping is a practice that dates back thousands of years, having said to have originated in China during the Song Dynasty (960 – 1279 A. D). These fish were kept for purely decorative purposes and gained much popularity, particularly among the rich due to their vibrant colours and peaceful demeanour. Since then fish keeping has spread all around the world from Europe to the Americas, and has become a luxury spared not only for the rich, but for all people as well.
The benefits of fish keeping are profound and widely acknowledged. A well-looked after aquarium brings colour and life to a home or setting, and brings a small piece of the natural world to the otherwise unnatural world we live in. To watch the flow of the water and the graceful, effortless movement of the fish can bring about a state of mental calm over the observer, evoke feelings of curiosity and joy, and has been known to be effective in relieving stress and even lowering blood pressure.
In order for our fish to keep us happy, we need to keep them happy in return. As well as creating and maintaining the right conditions for them to live in i.e. water conditions, temperature, environment, etc., adequate nutrition and feeding practices are also required for their optimum health and well-being. Fish that are under-nourished or malnourished cannot maintain health and growth, regardless of the quality of the environment they are in (Cho, 1999), so sound nutrition should be made a top priority for all fish enthusiasts.

Over the next few posts, I will be putting up notes on fish nutrition.

I’ve invited a colleague of mine, Ms Jessie Poon, to write a few words.

Ms Poon is currently studying nutrition at the RMIT. Subject areas covered in the course includes animal physiology, applied nutrition, toxicology and chemistry for life sciences. Her particular area of interest is health promotion through nutrition and diet, and biological sciences.

Ms Poon works at Boronia Aquarium (http://boroniaaquarium.com.au/), providing the vast variety of fishes, their nutritional needs utilising targeted feeding methods from the wide choice of foods available.

Ornamental fishes have travelled from afar and have undergone periods of fasting during their transit to your local fish shop. She has found that by supporting  them with good nutrition leads to  improved health and well-being of the fishes at Boronia Aquarium.