The diet secrets of fish with bait expert Dr. Paul Garner

With such a vast range of baits available, has it ever crossed your mind whether they resemble the natural food of coarse fish? 

What do fish actually eat when they are not feasting on our bait? The answer can give you a better understanding of what baits work, and when. 

The diet of coarse fish is affected by many things. Fish species is obviously important, but so is their size and the time of the year. Some fish are better able to make use of a sudden abundance of one type of food, while others have a more restricted diet. 

Coarse fish gain most of their sustenance from eating small invertebrates – everything from tiny bloodworms to tadpoles and snails. Generally speaking, larger food items are preferred. Most will be eaten either off the bottom or picked from submerged plants, and although fish are very good at ‘sorting the wheat from the chaff’, some silt and plant material will also be swallowed. However, they gain very little nutrition from this. 

Bloodworm for all

Bloodworm are found on the surface of silt and on the stems of plants. Smaller fish species such as roach pick them off for an easy meal. This is only half the story, though, as larger species may also become preoccupied with these tiny insects. 

Tench and bream have a particular love of bloodworm and feed on them by hoovering up the lakebed, sorting the edible from the rest in their mouths and eating only the animals. This shows just how dextrous these fish can be. No wonder they can at times eject a hook with ease. 

If you think that either species is in your swim, but you are not getting bites, tit’s possible that they are focused on bloodworm and a smaller bait could pay dividends. Red maggots or a small dendrobaena would be my choice.

Both species will move around lakes looking for fresh bloodworm beds where the amount of available food is high. This can explain the patrol routes that these fish adopt, and why some spots are more productive than others. Find a natural bloodworm bed and your chances of success will be good, especially if you plan to prebait.


Crunchy caddis

Often the mainstay of the diet of carp and tench, caddis larvae come in many different forms, from species that build intricate cases from grains of sand or bits of plant stem, to those that spin underwater webs, just like spiders. 

Most are around a couple of centimetres long, making them a decent mouthful for even quite large fish. Those with crunchy cases are normally found over gravel, while a case constructed from plants is great camouflage over silt, or amid weedbeds. 

The most common caddis that you are likely to see emerging in numbers at this time of the year is the black sedge. This is a cased caddis found widely in stillwaters, and is often the most numerous of all the caddis species. On some lakes where I have filmed underwater the bottom can be crawling with these critters, making a very easy meal for fish. 

When fish are feeding on caddis larger baits can be used, and the fish are likely to be less picky. Larger worms are worth trying, as are more easily seen baits, such as sweetcorn and punched meat. 


There are dozens of species of freshwater snail. Although we tend to think mainly of freshwater mussels, because they are so large, if you take a look into the margins of any river or lake you’ll see a whole range of different sizes and species. In fact the bottom is often covered with snails. 

Snails are eaten not just by carp and barbel, but other species too. Roach are lovers of small snails, but bream and tench seem less fond of this delicacy. 

If you retain a carp for a while, very often you will find the remains of snail shells in the sack that the fish has passed through its body. The shells are cracked open using the strong pharyngeal teeth at the back of the throat, allowing the juicy innards to be digested. 

It has long been suggested that one of the reasons hemp is so effective is because it resembles small black snails. This could well be part of the reason, but the strong taste has to play a bigger part. Boilies and bigger baits, such as meat, come into play when the fish are feeding on snails, the bigger bait being more in line with the fish’s natural diet.