Common Pleco In Low End Brackish

[JJ1234567]

I decided to go with 2 F8's and some bumble bee gobies. The only other thing I wondered is if a common pleco would be ok in low end brackish, 1.004 is what Ill be keeping it at, give or take a point or two. I know that I could put him in there either way, but I was wondering if it would shorten his lifespan, or make him uncomfortable. I know that high end brackish would be a no no, but I thought maybe down on the low end....let me know, and thanks ahead of time.

 

[SirMinion]

Absolutely not.

Plecos come from the deep amazon where the water is fresher than fresh. They have evolved for millions of years to thrive in freshwater without any trace of marine minerals.

To keep one in a tank with even a little salt can cause a slow painful death from organ faliure or ulcers and sores leading to slow death by dehydration as the electrolyte balance in its body is sent haywire.

(edit: as Neale says below, this is a generalisation and I may be exaggerating, but I am keen to get the point across )

 

[nmonks]

Broadly, I would agree with what SirMinion has said, but I would modify his answer somewhat.

A number of loricariid catfish do naturally inhabit slightly brackish water. They are not euryhaline in the sense of being tolerant of a wide range of salinities, but some are tolerant of low-end brackish. See, for example, this fact sheet from the Gulf States Marine Fisheries Commission, reporting Hypostomus plecostomus from fresh AND brackish water. Admittedly, Florida isn't its natural habitat, but given that these fish are not migratory, they are presumably only found in appreciable numbers in places where they live and breed.

http/nis.gsmfc.org/nis_factsheet.php?toc_id=191

Here's another example, for Hypostomus ventromaculatus, which according to Fishbase is found primarily and most abundantly in the brackish end of rivers and not "deep in the Amazon". Presumably this species is adapted in some way to this environment.

http/filaman.ifm-geomar.de/Summary/Speci...ry.php?id=48185

I'm not sure adding salt sends any physiological system "haywire" in the sense of making it operate in some random, improper way. When freshwater fish are kept in slightly brackish water they are stressed in proportion to the amount of salt added. The rate at which increasing salinity stresses a fish depends on its specific physiology. Most tetras, for example, will be stressed by tiny amounts of salt since they're adapted to mineral-poor environments. But some are notably tolerant of brackish water, including two common species, the x-ray tetra (Pristella maxillaris) and (if I recall correctly) the red-eye tetra (Moenkhausia sanctaefilomenae).

So simply adding salt to an aquarium with freshwater fish doesn't suddenly kill them, it stresses them, just as keeping them in the confines of an aquarium does, or not maintaining a large enough school, or not carrying out enough water changes. What kills freshwater fish is taking the salinity above their specific salt tolerance, which may be very low for some species (e.g. neons) but surprisingly high for others (e.g. many cichlids, which can live and breed in sea water).

Excess salt does not cause ulcers or sores. The idea salt water burns catfish is a total myth. Freshwater fish kept in too high a salinity become dehydrated, and die from organ failure, just as we do when dehydrated.

The problem of course is recognising the salt-tolerant freshwater species. This brings us back to your plecs. While there are, unquestionably, some species that will do fine at a specific gravity of up to 1.005, being sure that you have that species is very difficult. Plecs are tricky to identify even to genus, let alone species, hence the safest approach is to assume any given plec is NOT a salt tolerant species until you can positively identify it otherwise. Hence while I disagree with the SirMinion's statement on specifics, in general, his advice is sound.

Cheers,

Neale

 

[JJ1234567]

I appreciate the quick replies. I will take the pleco back with the rest of the fish, I will have to see if I can find one somewhere that does tolerate low salinity.

 

[SirMinion]

Blimey Mr Monks, I must be careful not to make sweeping generalisations when you're around!

I bow to your superior knowledge. *bows*

 

[chris_1127]

mr monks? i think you mean Dr...

 

[nmonks]

Well, yes, it's Dr., but of fossils, not fish, so it doesn't really count for anything here. For a start, there are at least four moderators who's postings I always enjoy reading and probably deserve honorary PhDs in aquarium keeping!

SirMinion -- didn't mean to be a know-it-all, just thought the clarification would be interesting. I remember a biology teacher calling me up on something when I was at school. Something about animals always having two eyes. He made it very clear to me that while generalisations are fine, biology is THE science of exceptions, so you have to be careful with them.

Your general advice -- plecs don't like or need salt -- is sound and I agree with you entirely. The interesting thing for catfish fiends might be quite how many catfish are adapted to brackish water. All the ariids and most of the plotosids, obviously, but also a fair number of silurids, ictalurids, even bagrids to name but a few. A whole subfamily within the banjo catfish family lives in estuaries and pretty much nowhere else. Catfish are really amazing in their ability to adapt to a wide range of habitats, and I think it comes as a surprise to anyone who isn't familiar with them, just how diverse they are. Truly wondeful fish.

Cheers,

Neale

PS. One of the brackish water banjos would make a superb companion for gobies. They are peaceful, non predatory, and able to tolerate a wide salinity range:

Aspredo aspredo
Platystacus cotylephorus