They where there but I just couldn't catch 'em

[Latimeria]

Narrh, "I live in hopes" theory is a none starter imo. Fish can't get minerals by scraping their flanks on rocks.

 

Latimera, where are you ?...tell 'em go on...tell 'em .

 

I'm trying to get my head round this theory. Active transport of dissolved salts across epithelial membranes from the surrounding water does occur with freshwater fish (requires energy), but the idea that solubility (and therefore availability) might be increased by physical contact with the substrate, to a degree that justifies the energetic expenditure, doesn't really make sense. The reaction of freshwater fish in an aquarium to NaCl salt at therapeutic levels isn't really relevant (and in any case it varies massively, in my experience they show initial discomfort and actively avoid areas of high concentration until it diffuses throughout the water column).

 

However, I have noticed that the fish on the Ribble have a particularly heavy load of Argulus this year, most of the fish I've had have been carrying numbers (even the dace, which is unusual), and these definitely do result in flashing and jumping.

[Guest I live in hope]

I'm trying to get my head round this theory. Active transport of dissolved salts across epithelial membranes from the surrounding water does occur with freshwater fish (requires energy), but the idea that solubility (and therefore availability) might be increased by physical contact with the substrate, to a degree that justifies the energetic expenditure, doesn't really make sense. The reaction of freshwater fish in an aquarium to NaCl salt at therapeutic levels isn't really relevant (and in any case it varies massively, in my experience they show initial discomfort and actively avoid areas of high concentration until it diffuses throughout the water column).

 

However, I have noticed that the fish on the Ribble have a particularly heavy load of Argulus this year, most of the fish I've had have been carrying numbers (even the dace, which is unusual), and these definitely do result in flashing and jumping.

Natural salts are certainly a mineral that fish seek out, and my observations with my own fish do bear that out. The reason that fish do this is perhaps because of the act of spawning and the need to replace certain salts that are expended during this period.

 

I could expand a bit more on salts with fishing in mind, but I feel that this although a Angling site may not be well received, especially with recent comments made that seemed to want to dispel this by your good self rather than looking at the probabilities and the improved catch rates when using salt, either as an additive to the hook bait or loose feed / ground bait.

 

However the bait companies are up to speed on this issue, and do in fact use salts in their products, so it is not new, but I am more interested in the reasoning as to why fish use salts.

[Tigger]

I'm trying to get my head round this theory. Active transport of dissolved salts across epithelial membranes from the surrounding water does occur with freshwater fish (requires energy), but the idea that solubility (and therefore availability) might be increased by physical contact with the substrate, to a degree that justifies the energetic expenditure, doesn't really make sense. The reaction of freshwater fish in an aquarium to NaCl salt at therapeutic levels isn't really relevant (and in any case it varies massively, in my experience they show initial discomfort and actively avoid areas of high concentration until it diffuses throughout the water column).

 

However, I have noticed that the fish on the Ribble have a particularly heavy load of Argulus this year, most of the fish I've had have been carrying numbers (even the dace, which is unusual), and these definitely do result in flashing and jumping.

 

 

It seems whenever the temp's are up and the flow is low there is a explosion of those lice. Maybe they can move throught the water and locate the fish easier in the low flow. The fish I watched yesterday where pretty obviously trying to rid themselves of the lice, first they'd speed up then scrape along the rock (to disslodge the lice first)and then shoot out of the water wriggling trying to flick them off.

[viney]

Narrh, "I live in hopes" theory is a none starter imo. Fish can't get minerals by scraping their flanks on rocks.

 

Latimera, where are you ?...tell 'em go on...tell 'em .

 

I'm sure I recognise "I live in hope"

 

No reference to fish 'scraping on rocks to get minerals' on google but plenty of references to them doing it to rid themselves of lice etc.

 

Funny you should say that Tigger, I thought that too.

[Vagabond]

the idea that solubility (and therefore availability) might be increased by physical contact with the substrate, to a degree that justifies the energetic expenditure, doesn't really make sense.

Particularly when you consider that any readily available soluble mineral present in the surface or immediate sub-surface of a rock will have been leached out by the river soon after that rock became submerged back in geologic time.

 

ILIH..... where did you find this information?

Edited July 11, 2013 by Vagabond

[Latimeria]

Natural salts are certainly a mineral that fish seek out, and my observations with my own fish do bear that out. The reason that fish do this is perhaps because of the act of spawning and the need to replace certain salts that are expended during this period.

 

I could expand a bit more on salts with fishing in mind, but I feel that this although a Angling site may not be well received, especially with recent comments made that seemed to want to dispel this by your good self rather than looking at the probabilities and the improved catch rates when using salt, either as an additive to the hook bait or loose feed / ground bait.

 

However the bait companies are up to speed on this issue, and do in fact use salts in their products, so it is not new, but I am more interested in the reasoning as to why fish use salts.

 

"Salts" covers a lot of compounds. When adding salts in crystal form (whether therapeutic NaCl or some of the mineral mixes I've had made up to replicate certain water conditions), hungry fish will react to the individual crystals as if they were food (but they'd do the same if I dropped a bogey into the tank), they reject them once they realise it's not food and can sometimes be seen to show irritation (head shaking, "coughing") subsequently until the branchial chamber has been flushed.

I've used plain old PVD, rock salt, marine salts and some of those I've had specially formulated, they all produce the same reaction initially in my experience in an enclosed space such as an aquarium (which is hugely different to natural environments, so shouldn't be compared).

 

I heavily salt my hemp, tares and other loosefeeds, it's how I store them (either that or in so much brown sugar that they are essentially crunchy hemp jam), and in the natural evironment there's plenty of evidence (only anecodotal) that it helps as an attractant for some freshwater fish. Don't believe the nonsense from some bait companies that it has to be their "special" salt that you use, I've used rock salt from a health food store or plain old cheap'n'nasty table salt without noticing any difference. I even tried salting casters to store them and they smelt fine, the only problem was they all ended up as floaters due to osmosis. Some of the best groundbaits are salty enough to kill maggots added to them, but in my opinion the salt just helps create a trail or concentration gradient to alert the fish that there's something worth investigating (note "my opinion", they could be attracted to sources of NaCl or other minerals that are physiologically beneficial). This would be acquisition of electrolytes through direct ingestion though as part of food, which is probably far more energy-efficient than having to utilise the active epithelial transport (which seems to be only used as a primary source of electrolytes during starvation).

There is some limited evidence that some fish do seek out certain minerals, and that is mostly anecdotal (I know of one case where a rock salt store adjacent to a river seemed to result in higher roach populations immediately downstream, but other explanations are possible for this). In any case, this was with a highly-soluble mineral.

 

Given that the bed of the Ribble in the area concerned is mostly gritstone, limestone or mobile particulate substrate (depends where you are), it's hard to imagine that there are sufficent soluble salts of any sort present that even a barbel equipped with a geologist's hammer for a pectoral fin could get any benefit.

Edited July 11, 2013 by Latimeria

[Guest I live in hope]

 

No reference to fish 'scraping on rocks to get minerals' on google but plenty of references to them doing it to rid themselves of lice etc.

 

Funny you should say that Tigger, I thought that too.

You need to look harder Viney, lice are more of a problem when fish are 'laid up, or torpid in the colder weather, not such a problem when these conditions prevail.

 

The 'flashing' you see is mostly as I suggested, try some rock salt in a aquarium or pond you will see for yourself, or you could just take Tigger's word for it

 

You say you thought that too about the lice /flashing, be prepared to reconsider.

[Guest I live in hope]

Lat,

Thank you for your summary, you obviously have good knowledge of the subject, and indeed you even quote of a high population of Roach near a rock salt plant, there is also evidence that Roach for instance enjoy a bracken visit once in a while, so certainly fish are tolerant of a higher than average saline in water, and indeed it is well considered to be value added health wise.

 

However I don't wish to argue my point with some on here, merely to accept that I believe that fish do seek out salt however they can obtain it, and disturbing the bed rock is an accepted way of doing so.

 

It's for me an interesting subject, and I would hope it could be debated as adults, but I fear that on here that might not be the case.

[viney]

You need to look harder Viney, lice are more of a problem when fish are 'laid up, or torpid in the colder weather, not such a problem when these conditions prevail.

 

The 'flashing' you see is mostly as I suggested, try some rock salt in a aquarium or pond you will see for yourself, or you could just take Tigger's word for it

 

You say you thought that too about the lice /flashing, be prepared to reconsider.

 

Care to point us in the direction of web based 'proof' to back it up then as 'I need to look harder'

 

And if you would care to read my post again I didn't say that they were ridding themselves of lice did I? I said there were more references to that and none (as far as I can see) to back up your claims.

 

Anyway I can see where this thread is going so I'm leaving it at that, wonder how long this username will last

Edited July 11, 2013 by viney

[Latimeria]

You need to look harder Viney, lice are more of a problem when fish are 'laid up, or torpid in the colder weather, not such a problem when these conditions prevail.

 

The 'flashing' you see is mostly as I suggested, try some rock salt in a aquarium or pond you will see for yourself, or you could just take Tigger's word for it

 

You say you thought that too about the lice /flashing, be prepared to reconsider.

 

All the research I can quickly lay my hands on indicates that Argulus numbers peak during the Summer regardless of habitat (using numbers recorded on fish hosts). This supports my own anecdotal observations (and those of people I talk to) that I rarely catch a fish with lice during Winter, whereas at this time of year, on the rivers I fish, most fish are carrying them.

Adding rock salt (or any NaCl) to a pond may result in flashing, however this is more likely to be down to direct irritation or the fact that the fish present are carrying a parasite load, and as the parasites are responding to the therapeutic chemical the fish become more aware of them (hence the scratching).

"Flashing", "glancing" or just plain scratching are known indicators of parasite loads or chemical irritation in fish husbandry. Marine fish do it as well, are they trying to put salts back into the rocks out of their bodies?

 

There's certainly an interesting question to be asked about the slower glancing behaviour of barbel which are thinking about food. Could be communication, could be removing any debris/parasites from where they have been resting, could have other physiological purposes (fish both yawn and stretch in preparation for anticipated activity, they might be giving their balls a scratch as well..), could be a combination of factors.

 

 

Lat,

Thank you for your summary, you obviously have good knowledge of the subject, and indeed you even quote of a high population of Roach near a rock salt plant, there is also evidence that Roach for instance enjoy a bracken visit once in a while, so certainly fish are tolerant of a higher than average saline in water, and indeed it is well considered to be value added health wise.

 

However I don't wish to argue my point with some on here, merely to accept that I believe that fish do seek out salt however they can obtain it, and disturbing the bed rock is an accepted way of doing so.

 

It's for me an interesting subject, and I would hope it could be debated as adults, but I fear that on here that might not be the case.

 

I haven't really got a good knowledge, just enough to spot flaws. Roach are often seen to migrate downstream in rivers during the colder months, but this might just be seeking more stable conditions than the upper reaches where extreme flow fluctuations, low temperatures and limited food availability make the Summer habitats undesirable, not necessarily anything to do with salinity. Some fish are euryhaline to a greater or lesser degree, but again, that's not really relevant to fish in Summer in the mid-reaches of a Lancashire river, nor is it "well considered to be value added health wise". I'm aware of some fish that can live happily all the way from pure freshwater to salinas where the water has a higher salinity than seawater, and yet others where salt at normal therapeutic levels would kill them in the time taken to read this thread, but that's all to do with levels of dissolved minerals.

Disturbing a non-soluble bed rock is in no way, shape or form an accepted way for fish to seek out salt, so if you want to debate this as adults you'll have to avoid making wholly-unsupported statements such as this.

Edited July 11, 2013 by Latimeria