now winters drawing in whats the minimum water temp they still work properly also heard elips pellets are good all year but thyre high in oil?

Not an expert on pellets but in general the lower the temperature gets the less oil will be released, but then as all fish are cold blooded then this will have a negative effect on the metabolism and therefore may be slow to respond to any bait. Most fish ( not all) rely on water flow to bring scent and thus food items to them. I would assume no matter what the temperature if a baits out there then some scent will be released however small. You then have to think how acute the species sense of smell is??? I am not sure with Barbel, i do know the eels is the most keenest. 1ml of scent in a water body 58x the size of lake constance. I could explain why this is but i could be here all day...lol

Probably not very helpful but just my thoughts, i am sure some of the more experienced barbelers on here will know.

Hi Chris, maybe you could answer a couple of questions based upon this?

Firstly; I always thought oil was immiscible in water. So how does it leak out as a scent trail? Ever noticed in stillwater, when you throw pellets in, the oil form a surface layer ( and actually calms the water somewhat too). So is the oily flavour actually available to the fish in any case?

Secondly that eel in that lake 58 times bigger than Constance...is it able to home in as flavour concentration gets higher? In a stillwater? I understand readily how sharks home in on rubby dubby, or barbel onto a bait, but in stillwater it is not just a matter of going against the flow.

As regards eels having such an excellent sense of smell: large olfactory organs and associated brain areas? Or something else?

Firstly with regard to the eel...

In most species of fish the two nostrils of each nasal cavity lie close together, in the eel they are far apart due to the very elongated shape of the what is known as the olfactory rosette, in other species this is round.
In the eel the rosette stretches from the anterior margin of the upper jaw to the anterior border of the eye where the posterior nostril is situated. The anterior, inflow, nostril lies at the anterior margin of the nasal cavity, it is tubular in shape and points downwards.

The olfactory rosette is formed from a number of folds, the Burbot which also has a strong sense of smell has about 30 folds, Rainbow Trout have has about 15. The eel has between 50 and 70 and in some cases possibly over 100. The posterior part of the rosette as a large amount of cilia, these enable strong water flow to pass through the cavity.In most fish species studied the olfactory surface area, measured as a percentage of the retinal area in the eye is between 14% and 140% in the eel this proportion reaches 623%. In conditioning experiments it was shown that the eel can percieve the scent of roses when diluted by 1:2.857 x 10 to the power 18. In addition there are only about 1800 scent molecules in 1ml of water the minnow ( which also has a keen sense of smell) needed a concentration 10 to power 10 times that strength in order to percieve rose scent.

The eels sense of smell enables the animal to follow a scent trail, orientation is achieved through trial and error ( through successive perception of differences) in addition to orientation on a horizontal plane, orientation on the vertical plane plays a big part. The use of its sense of smell has been exploited by baiting fish traps. The effectiveness is massively increase when baited, the eel isnt led in by the channeling effect of the barrier but as a result of attraction to the smell. Another interesting point is the actual scent of a particular water body and its attraction to elvers. In the study of four rivers, each was found to have water that was differentially attractive to glass eels. It was shown that waters with a high PH were more attractive, possibly showing that productivity in these waters was higher and so more prey species would be available.

You are quite correct regarding oil in water, a slick is often formed at the surface when oil is added, but all stillwaters are not strictly still. Wind action and convection can also come into play, you would be suprised how much movement, however miniscule there is. So if an oily bait is cast out, hits the bottom, the oil/scent leaches out and is carried both vertically and horizontally.

Water is a funny thing, it has a great deal of physical/chemical and biological properties that have an effect on things placed in it. PH, temperature being most notable, gases ie oxygen are more soluble the lower the temperature, yet minerals and other solubles are more soluble in warmer temperatures. I think on rivers the flow will carry it before it hits the surface, but thinking about it is it actually the oil that is the attractanct or is it just a carrier for the scent?? In which case are oils necessary? How much oil leaches out of natural baits? Its more likely to be amino acids etc which again are more soluble in warmer water.


At the end of the day, fish are adapted to live in their particular environment and to be honest they cope quite well ( until humans intervene).

Sorry if it all sounds confusing.

Originally Posted by cheef

now winters drawing in whats the minimum water temp they still work properly also heard elips pellets are good all year but thyre high in oil?

I've not noticed pellets, even high oil pellets becoming less effective in cold temperatures as such. However, high oil content is not considered to be good for the fish as the temperature drops.

Originally Posted by ChrisD

Sorry if it all sounds confusing.

Not at all. I greatly appreciate the rare chance to see subjects such as this explained in good biological detail.
The PH factor, in that alkaline rivers appear to be more attractive to glass elvers ,was particularly interesting. I had assumed that all glass elvers merely drifted with the ocean currents, until they arrived near a freshwater outlet, but the high PH preference suggests they must swim actively towards freshwater sources from some way out at sea.

Do the rosette cilia actually pump water through the nasal system in the eel? i.e. the system does not just rely on river currents, fish movement and the natural creep of smells through a water body?

Out of interest why did they choose rose scent? Roses do not exactly form a regular part of an eel's diet. Might the eel be even more sensitive to scents of its normal food items?

sonu baits 12mm crab pellets

The rose scent used was B- phenylethyl alcohol.
A few other points of note...

Water in which glass eels have been kept appears to be less attractive than water which has not been in contact with glass eels, older eels did not seem to have this effect on the water and appeared to increase its attraction for glass eels. This suggests that glass eels may be attracted by substances ( pheramones) given off by older members of the species.....a form of communication????

Substances attractive to eels have been shown to contain dissolved and undissolved organic material. To be destroyed by bacteria,and therefore ineffective, to unaffected by heat and not volatile. Salmon home by orientation on substances which are mostly volatile and which are destroyed by heat.

Japanese studies on the nature of these attractants have produced more conclusive results. For example....The biochemical components of a mussel that have been tested - eg -amino acids, quaternary ammonium bases, and nucleotides--only amino acids proved attractive although it must be stressed that not one of the 18 acids tested was effective on its own, it was only when used in a combination with another. Among the effective amino acids were Taurine, aspargine acid, threonine, serine, glutamic acid, glycine and alamine.

Other scents are just as effective, tubifex was still detected when only 5 worms with a total weight of 25mg were finely ground and and diluted in 6.67 x10 to the power 12 of water. In fact hungry eels would after a short time swim up and bite the hand that had been in contact with meat, when the other hand was placed in the tank it was ignored.

The ability to detect scent at low concentrations is different in winter, in late autumn/early winter the concentration must be raised by 10 to the power 6 before it can be percieved.

Attempts have been made to develop artificial baits which would appear attractive to eels without any conditioning. However most of the smells developed had any effect. Only Cibeton can be described as being particularly attractive ( not sure what this is) It is very expensive though. There are substances which repel however, especially substances used to preserve nets ( commercial) Carbolineum, diesel oil used as an emulsion, tobacco smoke ( debateable) ammonia ( over 0.0002%)

Many of the eels prey items eg smelt and crustaceans have been frequently observed to have an effect not only on yellow eels but also on elvers.Obviously some scents will cause a natural response in eels without conditioning but through an innate reaction. This has been shown with elvers in seawater when, after freshwater is added a marked increase in swimming activity occurs. If tapwater is added no reaction takes place. Natural surface from a lake proved to have a great effect but after being passed through a carbon filter it lost its attractiveness. So Glass eels arriving from the sea cannot have any experience of the various scents found in freshwater. The capacity to detect these scents despite the dilution by seawater must be innate.

I dont think water is "pumped" through the olfactory cavity, but i do know the nares are much more pronounced forming a tubelike structure, in effect the eel can smell in stereo.

Don't know how this relates to barbel as they, as we know, have other appendages to detect/taste. But i would like to know more about the anatomy/biology of barbel so if anyone has any good links etc please post them.

Sorry for banging on

Originally Posted by pie eater

sonu baits 12mm crab pellets

love these to great bait

good debate guys interesting stuff keep it coming

This is great stuff, well done cheef for asking the question, ChrisD for answering and JayZs for prolonging.