Can Freshwater Live In Brackish

[LolaLouie]

I have a friend who has freshwater fish but also has 2 puffers (not sure on the species but they're about 5 inches maybe a little more) in with them.. he adds a little salt to the tank.

I would really like a puffer but don't want to get another tank... can I do this?

 

[Truck]

no not really if you have any type of catfish, it will burn them. ive only ever heard of mollies being kept in salt

 

[LolaLouie]

Catfish as in plecos?

 

[Truck]

yes any type of catfish. they dont have scales they have boney plates that burn when the salt reaches them. read it in a book and on some websites

 

[PRW1988]

He may be using a conditioning salt on the tank to ruduce stress levels. Not as bad for catfish, but still a little risky.

 

[three-fingers]

Not a good idea, though there are freshwater puffers, most puffers are very nippy and tend to terrorize other fish. Your friend is probably just lucky.

Your friend adding a little salt to the tank is probably just using 'aquarium salt', which is a pretty useless gesture, see this topic: [URL="http/www.fishforums.net/content/forum/196353/Freshwater-Flounder-/"]http/www.fishforums.net/content/forum/19...ater-Flounder-/[/URL].

If you want pufferfish, try setting up a little 5gal dwarf puffer tank, totoaly freshwater and great little characters.

no not really if you have any type of catfish, it will burn them. ive only ever heard of mollies being kept in salt

How about marine catfish? There's a lot of good topics dispelling myths like "catfish cant do salt" around, very interesting reads .

Quite a few common freshwaterfish can live in mildly brackish water though, like x-ray tetras, guppies (which can live in full marine) and kribs. Search posts in the brackish section .

 

[kribensis12]

The only fish that i can think of that can be converted from fresh to brackish and saltwater are:
Mollies
Guppies
Scats
Puffers

 

[drobbyb]

The only fish that i can think of that can be converted from fresh to brackish and saltwater are:
Mollies
Guppies
Scats
Puffers

Yup. Mollies can be converted to full salt water if you raise the salinity slowly enough.

 

[Mr._Fishy]

Some freshwater fish can survive short term (and possibly long term, I'm not sure) in mildly brackish water. I believe there is a large cichlid of some sort that can do this, although the name escapes me.

 

[andywg]

Yup. Mollies can be converted to full salt water if you raise the salinity slowly enough.

A 30 minute acclimatisation will be more than enough to take mollies from FW to marine and nmonks often comments that mollies can be taken from fw and placed into sw with no acclimatisation. It would seem, therefore, that slow enough equates to almost instant in this matter.


And to return to the catfish comment about scaleless fish being burned by salt; not only do catfish exist in bracksih and marine waters (the families Ariidae and Plotisidae spring to mind) but so too do many eels (consider the moray eels). Eels do not have scales either yet manage to survive fine in marine waters.

So then, why are so many catfish so intolerant of salt in their water? It has to do with their osmoregualtory system (the system which maintains the internal salt levels through interactions at the gills for the most part). Many catfish and tetras have spent millions of years in the mineral and salt poor waters of South America and as such have an osmoregulatory system designed for keeping pretty much every mineral and salt the body wants inside. When they are placed in waters with significantly higher levels of salts and minerals (such as brackish and marine) then the body starts to take in far more than it wants at the expense of losing water; they become hypersaline.

The reverse occurs with Salt water fish; they take on too much water and lose salts and minerals becoming hyposaline (though studies appear to show that marine fish are more euryhaline than freshwater fish - that is marine fish live at a lower salinity better than freshwater fish live in a higher salinity).

So the above is why some catfish (as well as other fish) do poorly in salted water. It should be noted that there are variations in how well fish cope with levels of salt. To take the genus Corydoras as an example, some species perform extremely poorly whilst others appear to be able to survive well for some time at a specific gravity of 1.003 and above.

Finally, I am not aware of salt as a medicinal use (such as short term to deal with ich or some such ailment)being a problem.

 

[Dorkhedeos]

If they are about 5 inches, hopefully they might be south american puffers because these are freshwater. Got any pics?

 

[drobbyb]

By slowly enough I meant put them in a bucket with some tank water and acclimate them using the drip method. This will raise the salinity gradually. It just takes a bit of time.

 

[andywg]

By slowly enough I meant put them in a bucket with some tank water and acclimate them using the drip method. This will raise the salinity gradually. It just takes a bit of time.

Indeed, though if you look I point out that nmonks considers mollies euryhaline enough that one can just take them from FW and put them straight in marine with no ill effects.

 

[drobbyb]

By slowly enough I meant put them in a bucket with some tank water and acclimate them using the drip method. This will raise the salinity gradually. It just takes a bit of time.

Indeed, though if you look I point out that nmonks considers mollies euryhaline enough that one can just take them from FW and put them straight in marine with no ill effects.

Interesting.