Understanding a fish's taste

The next time you hook a bait remember one thing – the fish you’re trying to catch will probably be able to taste the metal it’s made from!

To help you understand this amazing ability, in this feature I’m explaining all about a fish’s sense of taste…

How fish taste

Some people find it difficult to separate the senses of taste and smell. After all, as fish live in water, surely taste and smell are the same thing?

Well, the fact is the two senses are different.

A fish has a very well developed sense of smell located inside its nostril. A fish also uses an array of taste buds to taste things in its environment.

Most taste buds on a fish are located on the lips, the roof of the mouth, gill arches and barbels but not, funnily enough, on the tongue.

Measuring just one 50,000th of 1mm, these microscopic sensors are tiny bumps that poke through the fish’s skin and protective mucus.

Taste buds can be triggered when they touch things, so the sense of taste is used on things the fish has picked up in its mouth or bumped into.

The sensitive tip is the bit that reacts to specific chemicals.

Here's how a taste bud works. The tiny receptor is just one 50,000th of 1mm where it pokes through the skin. When it tastes some food and passes the information to the fish's sensory system, a feeding response is triggered.

These taste buds, like ours, are sensitive to sweet, sour, salt and bitter chemicals. A fish’s taste buds are particularly sensitive to acidic tasting chemicals but their sensitivity to sweet and salt is generally less than ours.

Taste buds are also sensitive to the same chemicals as the fish’s sense of smell. So amino acids, bile acids and sugars all trigger the taste bud and tell the fish what they have found is food.

Betaine, for instance, an additive used by specimen carp anglers and which is naturally found in fishmeal, is one of several chemicals that trigger a strong response from the taste buds, so sparking a robust feeding response.

Baits which give off chemicals which trigger both senses of smell and taste will also provoke a strong feeding response.

This explains why fishmeal-based pellets, pastes and boilies are so effective – they have a smell and taste fish are massively stimulated by.

A lot of fish also have taste buds on their bodies. Scaleless fish like catfish have taste buds all over their bodies. Simply bumping into something can allow the fish to taste it.

Carp have taste buds scattered all over their head, barbels and on their fins. These body taste buds don’t release the strongest signal but they are good enough for a fish to know it’s bumped into something edible.

The taste buds which give off the strongest response are in and around the mouth.

The taste filter

Cyprinid fishes, like carp and roach, also possess a fleshy, muscular area on the roof of their mouths, called the palatal organ, which is covered in millions of taste buds.

When a fish sucks in food it uses this organ at the back of their mouth to taste it.

As soon as the palatal organ touches and tastes something edible, it automatically grips the particle of food.

With the edible stuff held tightly, the fish is free to reject the non-edible wreckage by blowing it out of their mouth. Edible particles are then swallowed.

If stones are sucked in with the food the palatal organ holds these while the edible particles are swallowed before blowing out the unwelcome stones.

It is no coincidence the pharyngeal teeth that mash up the food are located right next to this area. Once food has been filtered, it’s passed straight into the pharynx to be crunched up.

The palatal organ is probably the main reason why carp were once thought to be almost uncatchable and why the advent of the hair-rig has had such a big impact on the number of carp that are caught. Let me explain.

Carp have a very sensitive palatal organ, a large mouth and a strong exhale.

If such a fish sucked up a bait placed directly on the hook and tasted the metal the hook was made from on its palatal organ, they would reject the bait and easily blow it out of their mouth before the angler had any indication of a bite.

However, with a hair-rig the bare hook is free to prick the fish on its way out of its mouth as the fish tries to get rid of the bait, this massively increases the number of hook ups.

Scientific research has even shown that the sensitivity varies within a species – different strains of carp will have differing preferences for food.

One scientific study showed that European carp have a sweeter tooth than Asian carp.

Fish will also learn that particular tastes are associated with food and can develop a taste for unusual flavours not found in the wild.