Chemical defenses/toxicity in clown loach

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Dutch
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Post by Dutch » Tue Feb 12, 2008 2:38 am

Andyroo, if I have the time I will have a look. It will be an interesting orientation whatever the outcome.
It's a given here that 80% of all research funding applications are turned down, and PhD proposals take a year to get through.

I still have a lot of orientation to do. I've tried to come up with projects for my masters traineeship, but even that has been difficult.

Go! ChefKeith Go! :lol:

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Post by mickthefish » Wed Feb 13, 2008 6:55 am

here's the pic of the sterbai spewing a fluid/mucus from it's gill.
sterbai and gossei are one of the worst of the cory's for doing this, what we have found in some way it depletes the oxygen in the water and will kill all the other occupants of the bag/tank .
Image

this pic was given courtesy of Ian Fuller & CorydorasWorld.com

mick

Diana
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Post by Diana » Wed Feb 13, 2008 9:20 am

...it depletes the oxygen in the water...
Has this been tested by actually measuring O2 levels in the water and in the mucus?
Is the Cory hurt or sick?
Has it been determined that this stuff is actually toxic? Or do the other fish die of low oxygen?

If this mucus is specific to the gills, perhaps it does have something that attracts oxygen and helps the Cory to get oxygen from the water; its killing ability is incidental or secondary. I would think in a flowing stream it would get diluted too fast to do the fish much good as defense, and in an enclosed body of water it could kill the fish that created it, once it was released...

If it kills by being toxic but the Cory is immune to the toxin, then the oxygen depleting might be secondary.
38 tanks, 2 ponds over 4000 liters of water to keep clean and fresh.

Happy fish keeping!

mickthefish
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Post by mickthefish » Wed Feb 13, 2008 10:23 am

no it's not had any test its just an assumption thats what it does,
the female in the pic did die the male survived but only just.
these were perfectly healthy fish before they were caught and put in the show tank,
by the looks Diana this pic was taken at the show venue.

but this mucus/fluid is only done by a certain number of corys,
the two mention with the pic are i'd say the worst of the bunch.

a freind took all his breeders to an auction to get shut of them as well as their off-spring, the adults were dead or near to death when they were pulled out of the poly box but none of the youngsters were affected with the stress the adults shown.
all the fish were individually bagged.

i'll ask Ian if anyones tried to see what this thing coming out of the gills is.

mick

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Dutch
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Post by Dutch » Wed Feb 13, 2008 12:58 pm

That stuff looks very familiar to me, I lost several tanks of juvenile (three weeks old) carp with that stuff in the tank. We never found out what it was, but my guess is that it was released by the carp due to stress.
The gills, and any epidermal epithelium, can secrete mucus and stress can cause excess secretion.
I haven't read it yet, but I have a paper called 'Function of fish mucus' from 1994. It's old, but if I can spare the time I'll look it through.

I think Diana has a very keen observation. The natural situation vs. the bag they are transported in, or the aquarium they live in. There's a big difference there.

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Post by andyroo » Wed Feb 13, 2008 2:25 pm

Think of the overall defensive suite vs the environment into which they evolved. What predators would they be defending against in nature and how might this change with in life/growth/size, and in particular what would be the defining/keystone predator within those rivers at each size stage. Think also that these fish's colours become LESS pronounced as they age- does their schooling tendency change as well?

What are the major predators of Bornean creeks/rivers?

A
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Post by Diana » Wed Feb 13, 2008 11:37 pm

In any rather shallow, somewhat open creek I would list birds and mammals as predators. Mammals have well developed senses of smell and taste, so if the prey tastes bad they might be deterred. (Chefkeith, how did that Loach-Licking test come out?) I am not sure about birds or reptiles. Would a bad taste slow them down, or teach them not to catch similar fish in the future?
Reptiles might be found in deeper water, or shallow, sun-lit or shade. I do not think that taste or smell plays much of a role in dictating to reptiles what to eat, either. (I might be all wet, here, it would not be the first time)
Predatory fish might be found in waters where there is more cover for them to hide, but not all predators hunt from ambush.

Of what benefit is a substance that can kill the fish that produced it?
Well, if it only killed under conditions that are not found in nature (Confined to a tank or bag, poor water flow, recirculated water of limited volume...) then the killing is a secondary or lower ranking effect, not likely to occur often enough in nature to become an evolutionary force. Hmm...
If, for some reason wild fish were confined to a small pool (Dry season...Small enough water volume that this toxin might kill) then what is the potential survival rate, anyway? Isn't such a pool drying up? Wouldn't so few fish survive that the death-by-drying vs death-by-own-toxin is not likely to be a factor. The fish is dead. That it could not tolerate the toxin that it produced in such a confined location is not important. It cannot reproduce. If it was more tolerant of the toxin, it would still be dead, and still cannot pass on tolerant genes.

The same species of fish, in a larger body of water that can produce a bad tasting toxin might be spat out by a predator, or might make the predator so sick that the predator leaves others of the species alone. The fact that the bad tasting toxin might have killed the fish in another setting is immaterial. The toxin has done its job of protecting the species. That predatory mammal will now be leery of spotted catfish, and will teach its young that spotted cats taste bad.
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Post by andyroo » Thu Feb 14, 2008 11:13 am

in the case of the catfish, to provide evolutionary advantage you only need improve your reproductive success over generations, and that advantage only needs be very slight. If a nasty substance is produced in the egg mass that reduced predation to 90% from 93%, then that can work. If the hold-over effect of that ability in the egg is production of a mucus during stress that inhibits gill efficiency that kills 90% of adults under those specific conditions (ie: 1%/year over a 10 year life-span) then the trade-off remains positive for the egg-protector gook... for example.

In the CL, the mucus chemical appears to be a stress-reaction: not produced in happy animals, thus they can be eaten, but produced in animals chronically exposed to predation or related stresses, such as in a predatory tank or in a bag. Remember how your other clowns freak-out when one is caught in the filter- there's a chemical signal produced at least. Do other loach spp do the same when a school mate is damaged/killed? Not that i've seen, nor have i seen this reaction in other families/fish.
"I can eat 50 eggs !"

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Re: Chemical defenses/toxicity in clown loach

Post by Dutch » Fri Feb 15, 2008 2:50 am

andyroo wrote: I'd watch the arawana go in for a taste, then back
off at the last moment.
Just a thought, but these two species know each other. Arowana and Clown Loaches both come from Borneo and Sumatra. Maybe an instinctive reaction?
It doesn't explain the behavior of the other fish yet, but I like that there is a relationship between these two species.

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Post by andyroo » Sat Feb 16, 2008 11:56 am

Sorry Dutch,
Silver arowana...
South America.
No natural connection.
A
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Post by Dutch » Sat Feb 16, 2008 4:24 pm

Okay, that rules that out. It's just the way I think about these things, I try to survey all possibilities. :wink:

mjbtin
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Re: Chemical defenses/toxicity in clown loach

Post by mjbtin » Fri Jun 12, 2020 12:01 am

Hi all
Long time lurker :D often visited for great info and advice but never posted.
The other evening one of my clown loach managed to get stuck in a hole in a resin log ornament.Clearly in great distress as both spines fully out,lifted up the ornament to see if I could help ease the loach out but with no luck was stuck solid with both pectoral fins through the hole.It was then I noticed the copious amount of clear gel like slime which had been produced because of the stress.Last resort managed to break the hole with some wire snips and freed the loach.
The next morning checked on loach but looked to be doing fine then noticed a dead fish on the eheim pump after closer inspection it was both my torpedo barbs and 2 of the 12 tiger barbs.Done the usual checks water params heater all ok, 25% water change cleaned prefilters and added a polyfilter and so far no more fatalities.
My conclusion(no proof non scientific) is that the slime was the culprit whether it is toxic in the water,toxic if ingested or coats the fishes gills stopping the fish from breathing dont know.
In hindsight I should have removed the ornament and cleaned all the slime off may have had a different outcome.

Regards Martin

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