Feeding and Digestive Functions in Fishes

1st Edition

IX. Metabolism
In adaptation to diet, the major differences are seen in the structure of the mouth and the teeth, the gill rakers, the pharynx, the stomach if present and in the length of the intestine. Bones, teeth and scale tissues require lots of minerals. Mostly, fish are able to take in the food they need within minutes of their feed. The size and fullness of the gall bladder is indicative of feeding status in fish. Alternative fish Foods - Information about suitable fish foods you can buy in your grocery store. Bile is excreted from the bladder to the intestine via the bile duct. Generally meats consist of about 20 percent protein, 20 percent fat, and 60 percent water.

A. Digestive System

Digestive System in Fishes (With Diagram)

Care must however be taken to ensure that these food varieties do not carry infections, such as germs or other parasites, in them. This is very difficult to ascertain, unless you culture your own live food.

So beware when you feed live food to your fish. Food for the fish has to encompass a large number of nutrients. All these together make your fish healthy and able to adapt to changing conditions in the aquarium. Remember, the healthier the fish, the more resistance will they have to disease and infections.

Didn't find the info you were looking for? Register for free and ask your question in our Aquarium forum! Our knowledgeable staff usually responds to any question within 24 hours. Alternative fish Foods - Information about suitable fish foods you can buy in your grocery store. Brine Shrimp Hatchery - How to make a simple plastic bottle brine shrimp hatchery, in pictures. Choosing food for and Feeding Fry - An introduction to feeding fry. Cultivation of some common live food - A guide about how you can cultivate some common types of live food in your home.

Culturing Microworms - An article on this useful live food for fry and small fish. Feeding fish - An article about feeding fish and which factors that stimulate fish to eat. Fish feeding habits - An introduction to the different feeding habits different types of fish have. Fish food — an introduction - A comprehensive discussion of fish foods. Growing adult Brine shrimp - how to grow adult Brine shrimp Microworms - Microworms are easy to cultivate and are excellent live food for small fish or growing fry.

Raising and Growing Large Brine Shrimp - How to build a brine shrimp hatchery, and how to feed and grow the shrimps. Raising Daphnia - How to culture and use daphnia.

Raising mealworms for animal food - Yellow mealworm larvae or adults serve as food for fish, reptiles, birds and other animals Raising Vinegar Eels - How to culture this easy and inexpensive live food. Combined Worm Culture - Grindal worms and red worms can be cultured in one container together, thus providing live food for different sizes fish Tropical fish food - An introduction to fish food for beginners.

Types of fish food - A guide to the basic types of fish food available. Feeding your fish vegetables - Fresh cooked high fibre vegetables benefit the digestive systems of many fish. Protein and fish Protein is the single most important nutrient that the fish needs to grow. On a dry-weight basis, this makes up the maximum weight in their body structure. Amino acids are derived from proteins and the fish uses them to make new body tissues as well as enzymes.

Fish are very adept at converting food to body tissues. That is why fish need lesser amounts of food than do most other animals. Carbohydrates are almost non-existent in the food intake for many fish species, since energy is also derived from proteins.

Irrespective of their main dietary requirements, the digestive systems of fish are very similar. All have a mouth, oesophagus throat , and areas for the absorption of food components fore and midgut and compaction of indigestible waste material hindgut.

In adaptation to diet, the major differences are seen in the structure of the mouth and the teeth, the gill rakers, the pharynx, the stomach if present and in the length of the intestine. In carnivorous fish or those with a meat-orientated omnivorous diet there is a definite stomach foregut whilst herbivorous or plant-orientated omnivores have no stomach but rely on a much extended midgut area. These two situations are shown below. Digestive system of a Carnivorous Fish.

Digestive system of a Omnivorous Fish. Additionally carnivorous fish have extensions to the upper part of the midgut known as pyloric caecae. Two other internal organs are associated with digestion, namely the liver and the gall bladder, located anteriorly to the stomach or anterior section of the midgut. Before being digested, the fish food, whether live or in the form of a pellet, has to be caught and positioned before being 'swallowed' - this is the function of the mouth.

In carnivorous or predatory fish teeth may be present on the jaws, tongue and inner mouth buccal cavity - these teeth do not bite or crush food but simply hold it and prevent escape. Herbivorous fish or those which feed on hard-shelled prey may have pharyngeal teeth to aid in crushing the food before it enters the stomach. For those fish species with a stomach, two areas can be identified - a cardiac area anteriorly i. In stomachless fish, the wall of the anterior midgut secretes digestive enzymes but not hydrochloric acid.

In carnivorous fish the intestine is relatively short whilst that of herbivorous fish, which tend to lack a stomach, is long and much folded to increase the contact and absorption time. At the anterior end of the midgut a number of blind ending tubes may be present - these are the pyloric caecae. The mechanism of feeding behaviour in fishes is very complicated. There are generally several kinds of stimuli for feeding. The common factors affecting the internal motivation or drive for feeding include season, time of the day, light intensity, time and nature of last feeding, temperature and any internal rhythm.

The visual, chemical, taste and lateral line system also control the momentary feeding act. The interaction of these groups of factors determine when and how a fish will feed and what it will feed upon. The role of visual and olfactory factors in connection with feeding behaviour has been studied by experimental conditions by Groot He found visual, chemical and mechanical sense organs in Pleuronectidae, Soleidae, and Bothidae belongs to the family of flat fishes, Pleuronectiformes.

Soleidae are polychaet mollusc feeder, feed during night, find their food mainly by olfactory clues, but still have the capability of finding their food visually, Table 1. The barbels help the fish to locate food grubbed from soft bottom material. Amongst teleosts, about The common examples are Labeo species Osphronemus goramy, Sarotherodon mossambicus etc. Herbivorous fishes have long and coiled intestine Fig. The fishes in contrast to herbivore have shorter gut, the intestine is straight, very little coils are present.

Some of the carnivores possess intestinal caecae. They prey on small organisms and consume high percentage of animals such as copepods, dafnia and insects. The examples of carnivorous fishes are Walla go attu, Mystus seenghala, Mystus cavassius, Mystus vittatus, Channa striatus, Channa marulius, Channa punctatus, Notopterus chitala, Rita rita, etc.

Fatty acids and fish