Freshwater Flounder?

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moeberry

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Hi
I saw a fresh water flounder in my local pet shop. I was told that it would do fine in my fresh water tank, but upon researching on the net, I found that most so-called freshwater flounders need some salt in the water as they grow. So my question is how can I tell if it is one of the true fresh water fish or if it will need salt later on?

Please excuse me for not knowing the proper names.

Moeberry
 
Hi
I saw a fresh water flounder in my local pet shop. I was told that it would do fine in my fresh water tank, but upon researching on the net, I found that most so-called freshwater flounders need some salt in the water as they grow. So my question is how can I tell if it is one of the true fresh water fish or if it will need salt later on?

Please excuse me for not knowing the proper names.

Moeberry


I kept a true freshwater flounder, a brachirus harmandi, for some time. The give away was that it did not have a paddle tail, and the underside was mottled. Have a look on fishbase (www.fishbase.org) and search for all fish with the common name flounder. It may take some time...

Brachirus pan is one of the most frequently traded, although, I think the scientific name was changed for that some time ago.
 
As Fella mentions, the tail fin is a good clue. Where most of the American soles (family Achiridae) have a large, paddle-like tail, the Asian soles (family Soleidae) tend to have a small tail that blends almost imperceptibly with the fins around the edge of the body, often tapering to a point. I've got a listing of some of the most common species in my FAQ.

Almost without exception, the species sold in the US is the subtropical hogchoker sole Trinectes maculatus, a species that needs brackish water. In Europe things are a bit more mixed, though species of Brachirus do seem to predominate. These are extremely difficult to identify to species level, the exception being Brachirus harmandi which, as Fella says, has a mottled underside (all the other species have plain pink or white).

Unless you know better, keep a sole in brackish water at SG 1.005 with moderately to hard water and a pH around 7.5. This will do freshwater species no harm at all and will benefit brackish water species immensely. Such a tank could also house guppies, mollies, gobies, etc. so doesn't cause any problems in terms of building a community. Plants aren't an issue, because soles want plain sand (not gravel) so you may as well skip plants or use species attached to wood/rocks like Java fern, Java moss, and Anubias.

Cheers, Neale
 
I have had freshwater flounder before, THey do well in a simple freshwater aqaurium. However, most freshwater fish do like some salt. It adds electrolytes, and slightly alkanizes the water. Use only salt made specifically for aqauriums as table salt can be harmful and add only the amount that the box tells you for every gallon of freshwater.
 
However, most freshwater fish do like some salt. It adds electrolytes, and slightly alkanizes the water. Use only salt made specifically for aqauriums as table salt can be harmful and add only the amount that the box tells you for every gallon of freshwater.
This is just old school fishkeeping without any science to back it up. Some freshwater fish are highly intollerant of salt in the water even in the short term. In the long term you are placing an increased pressure on the fishes' osmoregulatory systems as they are having to process water with more salt in it than they are evolved to do so.

Which electrolytes exactly are added, and why are they necessary for freshwater fish?

Also, aquarium salt is just sodium chloride, exactly the same as any other sodium chloride. So long as your table salt has no other additives then you can use it (and it is cheaper).

Do a search on salt in the main forum and you will find a number of scientific based results on why aquarium salt is little more than snake oil.
 
Thats your own opinion, and I couldnt' disagree more. Fish like some degree of electrolytes. Some are intolerant, but even those like some amount because it encourages slime coat production and thus protects the fish from bacteria. Actually thats the main benefit of salt, It encourages the slime coat to build. It's not oldschool, it's extremely current. I'd always reccomend some salt.

Ground contains salts, rivers ruun over the ground. Any river in the world that you go to, will have some salts in it.
 
Fish like some degree of electrolytes.

You still haven't said exactly which ones they are and why the fish want them. Until you can I think this is a null argument.

Some are intolerant, but even those like some amount

No. See, the word "intolerant" means they cannot tolerate it. In other words, some fish die with an extremely low amount of salt in the water. Previousl,y Bignose has found studies showing some species of cory die in extremely low amounts. These fish cannot be considered to be "liking the salt in small amounts" if they are dying from it.

because it encourages slime coat production and thus protects the fish from bacteria. Actually thats the main benefit of salt, It encourages the slime coat to build.

The main way that most (if not, all) slime coat additives work is to irritate the skin of the fish into producing more slime coat. Where is there any evidence that salt helps the slime coat rather than irritating the fish into producing more?

It's not oldschool, it's extremely current. I'd always reccomend some salt.

The use of aquarium salt came about from two outdated beliefs in early fishkeeping:

1) As "old water" was considered good, to prevent problems from nitrates and nitrites in the water, salt was added. This dulled the effects of poisoning the fish with the aforementioned nitrogenous waste compounds;

2) As FW fish maintain an internal salt level higher than the water around them, it was considered less stress on them to have a higher level of salts in the water. Unfortunately these earlier fishkeepers forgot that FW fish have evolved through millions of years to osmoregulate in the waters effectively devoid of salts, and by adding more it can cause problems with the osmoregulatory functions of the fish.

Nowadays people realise that water changes are far better than old water, and people try and keep the fish in water as close as possible to that in which the fish occur naturally.

Ground contains salts, rivers ruun over the ground. Any river in the world that you go to, will have some salts in it.
Indeed. But your tap water already has more salts in it than most of the South American waters. Freshwater rivers in SA (and most of Asia) contain less than 1ppm sodium chloride; an amount so small that even scientists don't bother to recount it any more accurately than "<1ppm" in degree level ichthyology texts.

Now then, since you claim the salt is so good for the fish, can you find any scientific evidence to support your statements that all fish benefit from salt in the water, even those that it kills in small quantities?
 
"Indeed. But your tap water already has more
salts in it than most of the South American waters."


Not my tap water. And no they aren't intolerant in general, they are intolerant to CERTAIN levels. Electrolytes is a self explanatory word. It means ions from the periodic table of elements that fish use in nature to help build their slime coats. These include sodium +1, Magnesium +1, Chloride +1, Iodide +1 among others. Is that specicfic enough?

And no it has nothing to do with iritationof the skin to force more slime, the slime that the fish use are made from compounds containing these ions. When there are not enough of these ions in the water, the slime coat is limited, if there are too much, and the fish can remove them, they will begin froming harmful compounds as the fish cannot find the other neccessary ions to bond with these. Ions need to bond because they want a noble gas configuration. If there are not enough healthy ions to connect to these salt ions, then other harmful ions will begin to connect to these extra ions and this is what harms the fish if they cannot filter the new compounds.
 
Not my tap water.

So you can test the level of salt in your water to a higher degree than scientists even bother mentioning in a degree level text. I hope you can forgive me for doubting the above assertion.

And no they aren't intolerant in general, they are intolerant to CERTAIN levels.

Yes, and in some fish that level is extremely low.

Electrolytes is a self explanatory word. It means ions from the periodic table of elements that fish use in nature to help build their slime coats. These include sodium +1, Magnesium +1, Chloride +1, Iodide +1 among others. Is that specicfic enough?

How will magnesium be introduced into the water by the very nearly pure sodium chloride in aquarium salt? Or iodode? Aquarium salt is nothing more than table salt: sodium chloride, and often includes an anti caking agent to make it pour nicely. I do not

And no it has nothing to do with iritationof the skin to force more slime, the slime that the fish use are made from compounds containing these ions. When there are not enough of these ions in the water, the slime coat is limited, if there are too much, and the fish can remove them, they will begin froming harmful compounds as the fish cannot find the other neccessary ions to bond with these. Ions need to bond because they want a noble gas configuration. If there are not enough healthy ions to connect to these salt ions, then other harmful ions will begin to connect to these extra ions and this is what harms the fish if they cannot filter the new compounds.

Do you have any scientific texts to back that up? I find it hard to believe that fish such as South American Characins that live in salt and ion poor waters will suddenly feel so much better with salt in the water. I also find it hard to believe that fish that are evolved to live in waters free of these ions in the wild will suddenly have problems in an aquarium setting.

nmonks has previously commented on the slime coat:

Fish produce extra-thick slime coats when their skins are irritated. If you want a human analogy, it's getting a callous on our feet when we walk barefoot a lot or in poorly-fitting shoes. Our skin responds to the stress by developing a coat of dead skin cells that protect the living tissues within. Likewise, where fish are irritated, their produce extra mucous on the skin to protect themselves. A fish should have a perfectly adequate slime layer under its optimal conditions (which, for angelfish and discus, would be very soft water at about pH 6). Secondly, I do not dispute that salt is useful for treatment. But there's a difference between using salt as a short-term tonic in the aquarium and using salt all the time. I don't know any professional aquarists who recommend the latter. Rather, experienced aquarists put the accent on water quality and trying to match the water chemistry of the fish's natural habitat.

Interesting to note the point I have put in bold above.

From reading Biology of Fishes 2nd edition by Bond, I note that the slime coat (or mucus) consists largely of glycoproteins that can absorb large amounts of water. I am no expert on glycoproteins, but my short reading indicates that sodium or chloride ions are not component parts (their make up is of a protein and a carbohydrate). I also can't find any references to fish needing these electrolytes in the water (including the ones not present in aquarium salt) in order to create mucus.

In the two degree level ichyology biology texts I have (one being mentioned above, the other being Ichthyology: An Introduction to Fish Biology 5th Edition by Cech and Moyle) the only mention of electrolytes is in relation to the electricity producing cells in electric fishes. The only mention of ions is in relation to osmoregulation, and I have detailed above that increased salt levels will place unnecessary strain on freshwater fishes evolved for water without salts in them.

However, if you have more recent studies that the above two texts would not have considered when writing I would be interesting to see them.
 
How will magnesium be introduced into the water by the very nearly pure sodium chloride in aquarium salt? Or iodode? Aquarium salt is nothing more than table salt: sodium chloride, and often includes an anti caking agent to make it pour nicely. I do not


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Because these aquarium salts are sea salts, and the majority of sea salts are actually magnesium salts, not sodium salts.
 
Because these aquarium salts are sea salts, and the majority of sea salts are actually magnesium salts, not sodium salts.
Aquarium salt for freshwater fish (as sold by your lfs for freshwater aquaria) is pretty much pure sodium chloride.

Sea salt is around 75-80% sodium chloride. The rest of the elements buffer the water increasing alkalinity and raising the pH towards 7.8-8.2.

Those last two factors make sea salt completely the wrong thing to add to any tank containing soft water fish that require low alkalinity and a pH closer to 6.
 
sodium chloride.

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Sodium Chloride is table salt.

Actually you were right about there being more of this than magnesium salts in the ocean, but Magnesium is second to sodium compounds in the ocean.
http://en.wikipedia.org/wiki/Seawater

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And you can continue to argue until your hearts content, but I always strongly encourage using salt in freshwater aquariums as long as you follow the instructions on the salt container and as long as it is specifically made for aquariums. You can think as you like, but I use salt with great results and I will continue to give it as advice to everyone I meet.
 
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And you can continue to argue until your hearts content, but I always strongly encourage using salt in freshwater aquariums as long as you follow the instructions on the salt container and as long as it is specifically made for aquariums. You can think as you like, but I use salt with great results and I will continue to give it as advice to everyone I meet.


I applaud you for sticking to you guns in the face of overwhelming logic and scientific fact. Bravo.
 

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