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I'd like to hear your experience with these fish... tank setup, feeding, longevity etc.

I've collected some G. cenia from the wild a while ago... they did ok at first, but ate little and died after a few weeks.

wait till Marc van Arc shows up; he's got those, and experience with them; but most problems with this fish arise from two things:
too high temeratures
too little oxygen.

they "age" rapidly when kept too warm (like running for life on 78 rpm when they should be 33 ), and with insufficient oxygen they dont last long either.

Marc's got a few that seem to last quite a while.

I've imported them quite a few times. Usually they arrived close to DOA and D'ed shortly after A. Once I managed to keep them alive for a couple of months, but they succumbed to some kind of bacterial infection thereafter.

Sid may be right about the O2 and temperature. My view is that they -- like many Sisorids -- are fragile fish in the best of circumstances and with the stress of capture, storage and transport, are extremely prone to bacterial and fungal infection.

I suspect that if you can get relatively healthy fish to acclimatize successfully for 2-3 months, they should not be impossible to keep alive. But I don't have the patience to play Florence Nightingale with Gagata cenia any more. I'm told that G. viridescens is hardier.

Dinyar

Most members of the Nangrina, I suspect, are strongly electroreceptive. They appear to have numerous pit organs, which I think are electroreceptors, and many of them have heads that have considerable areas (usually on the lower jaw) that have a fair amount of adipose tissue. I surmise this may serve as some kind of electrical insulation.
This may have nothing to do with the reason they die so easily on capture, but I like to think that it does.

Silurus wrote:Most members of the Nangrina, I suspect, are strongly electroreceptive. They appear to have numerous pit organs, which I think are electroreceptors, and many of them have heads that have considerable areas (usually on the lower jaw) that have a fair amount of adipose tissue. I surmise this may serve as some kind of electrical insulation.
This may have nothing to do with the reason they die so easily on capture, but I like to think that it does.

An interesting insight. I think of the Hughli and the lower Ganges delta as pretty turbid. I recall you collected G cenia on both your trips to India. Would you describe the places where you collected G cenia as low-visibility environments where electroreception would confer a special advantage?

Interesting theory about the electroreceptors...

My fish were caught from the Ganges, in fairly clear water, about 1-1.5 m deep. I guess they could use the electroreceptors to detect inverts in the sand...??

Interesting thing was the only way to catch them was to fish at night or at just before dawn. According to the local fishermen, they head to deeper waters during the day.

In addition to the high O2, low temp rewuirements, I think:

1. They are specialised to very low light environments and are stressed out by the light levels in most tanks. Even ambient lighting may be too much for them

2. They are specialised feeders. Mine only ate tubifex and that too with great reluctance.

I might offer the opinion that they may be chemo-receptors for the schreckstoff (alarm or fright substance) mechanism typically found in schooling fish. Gagata are strongly schooling fish unlike the other well known electroreceptive fishes found in nature (Malapterurus, Electrophorus, gymnotids, etc). They are skittish fish and when you alarm one, the whole tank goes into a frenzy.

G. gasawyuh of the Thai Salaween are found in highly migratory shoals along sandy (light colored, thus large irises) shores. In winter, low 20's C, 50- 80 cm visibility. They are constant foragers (benthic) and incessantly swim in a most unconservative manner (no "hovering", no pausing). Coupled with higher temps in the aquarium, this has a high energy cost and unless you feed them constantly all day, normally aquarists cannot keep up with their energy demands (ie ad lib feeding), and they get progressively thinner. If you have a stationary gagata, it's too weak. The relationship between dissolved oxygen and temperature goes without saying, they're inversely proportional.

The pit organs are too large for chemoreceptors, I think (especially when you look at those on the snout of a Nangra). Furthermore, they are heavily concentrated in the snout region, especially on its ventral surface. Not an area where one would concentrate chemoreceptors for alarm substance. I think they might have some role in prey detection.
Many catfishes are electroreceptive, but not electrogenic (being able to detect a current and actually generating one are two different things).

Point taken. Are these structures also found in related but more sedentary bagarius and glyptothorax?

No, as I mentioned earlier, I've only seen it in the Nangrina. It's not very evident in both Gogangra and Gagata, very strongly evident in Nangra.

Fascinating discussion.

I kept a trio for two years. Small tank, on their own, fed frozen brineshrimp, lost them to the heat of a Scottish (!) summer. They were kept at 74F in a tank with a regular internal filter but always with an airstone too.

Jools

What can I add?
They need cooler water, a strong current and loads of oxygen. Things an LFS doesn't always supply. When I got mine, they had already been in a bag for 22 hours. The water was off-white by pollution and the fish were rather dazed (and confused). So I had little hope they would survive. But they did, although during the last 1 1/2 years the group of 7 gradually decreased to 2 at this moment. They are very fond of bloodworms and also have no problem with flakes; actually I don't think they are fussy eaters. In my view the largest problems are temperature rises: these urge the fish to live much faster than normal, with the ultimate result of death by wearing itself out. I have the same problem with my Pseudolaguvia shawis (3 still alive from 10 in one year).
Therefore I have promised myself not to buy these fish again.

About pits: may they be some form of movement-detecting pits more or less similar to Malawi peacocks [Aulonocara]? That cichlid genus can detect inverts in the sand by "listening" to inverts' movement.

I have kept gagata schmidti very successfully for many years. Yesterday I lost my last 2, which were about 8 years old, maybe older. I have found them to be brilliant fish, prefering a shoal, caves, lower light conditions and moving water, and feed on anything but especially love bloodworms and tubifix. They are such peaceful fish and leave even the smallest alone, and are constantly active. I have had a bacterial infection of some sort in the tank and have lost many fish, so decided to remove all to another tank and strip main one, and treat fish in smaller tank. Gagata got distressed, and one started bleeding behind an eye, and other one looked wobbly and eyes cloudy and puffy. Both died shortly after. Suspecting bacterial infection? Nothing written about sexing these fish, though from my own observations I would say the females are blacker and fuller bodied, the males more silver and slimmer. I would dearly love to get some more, but don't know where to get some. Local fish shop doesn't have it on their suppiers lists. Any advice?

[quote="Natalie]I would dearly love to get some more, but don't know where to get some. Local fish shop doesn't have it on their suppiers lists. Any advice?[/quote]

Natalie, I've never heard of someone keeping them for so long. You have my respect for that. Well done.
As for your question: I don't know if the English wholesalers get fish from the Netherlands. The largest wholesaler here, Ruinemans, stocks them regularly.
Perhaps you can ask if someone is willing and able to order them there.
Best of luck.
Marc

Wow Natalie, that is good fish keeping

Not to detract from your accomplishment, both genera are equally hard to maintain in aquaria, but isn't Gagata schmidti a Glyptothorax?

Gagata schmidti is a name commonly misapplied to the G. cenia. It is actually the Sumatran Glyptothorax often misidentified as G. platypogon.

Silurus wrote:It is actually the Sumatran Glyptothorax often misidentified as G. platypogon.

You lost me a bit there HH , did you mean that the true Gagata schmidti is often misidentified as Glyptothorax polypogon?

Or did you mean that a Sumatran Glyptothorax is misidentified as Gagata platypogon

Sumatran "Glyptothorax platypogon"=Glyptothorax schmidti
"Gagata schmidti"= Gagata cenia.

Aah thanks