Arius Seemanni / Arius Jordani

[Scatta]

Yet another question from me.

Is the fish Arius seemanni the same as Arius jordani? If not, what is the difference between the two and how can I identify them? Sorry if this is a daft question.

Is there any member of the Arius genus that doesn't grow very large? I like the fish, but feel my aquarium is not large enough for them (Rio 240).

 

[nmonks]

Is the fish Arius seemanni the same as Arius jordani? If not, what is the difference between the two and how can I identify them? Sorry if this is a daft question.

Yes. It's actually called Hexanematichthys seemanni now (a mouthful, I know, and pronounced: "hexa neema tick thiss").

Is there any member of the Arius genus that doesn't grow very large? I like the fish, but feel my aquarium is not large enough for them (Rio 240).

Most species of Ariidae are even bigger. Colombian shark catfish apparently get to 35 cm in the wild, and in aquaria they seem to be around 30 cm when fully grown. Personally, I'd consider a 240 litre tank to be a bit on the small side for what are, fundamentally, large, very active, schooling fish.

An alternative might be Plotosus lineatus, a fish usually sold as a marine but perfectly happy in brackish water (and as adults even freshwater, for a while). Although equally big, adults are sluggish and lurk about in caves all day.

Cheers,

Neale

 

[Scatta]

Personally, I'd consider a 240 litre tank to be a bit on the small side for what are, fundamentally, large, very active, schooling fish.

I totally agree. As much as I would like to keep them, it's not fair to cram them into a small tank for my own amusement.

Do the Plotosus lineatus need to be kept in large groups as the link provided states they shoal as groups of around 100 fish in the wild (obviously, this isn't possible in aquaria). Also, will they be okay in an SG of 1.008 (which is what my brackish tank is currently at)?

 

[nmonks]

Do the Plotosus lineatus need to be kept in large groups as the link provided states they shoal as groups of around 100 fish in the wild (obviously, this isn't possible in aquaria). Also, will they be okay in an SG of 1.008 (which is what my brackish tank is currently at)?

Ah, this is where it gets interesting. As juveniles, they are schooling fish. But once they get to about 10 cm or so, they become more territorial, and eventually become loners. So, what I'd try and do is either find a specimen a marine aquarist has got bored of (they do lose their colours a bit as they mature) or else just risk keeping one knowing that for the first 6 months it'll be rather nervous and shy. With luck, as it grows and becomes more settled, everything will work out okay.

Personally, I'd bump the SG up to 1.012 if I were keeping a juvenile. It does seem the babies live in the sea and only the adults move into estuaries and freshwater. While I'd expect it would be fine at a lower SG, I can't guarantee that.

Cheers,

Neale

 

[Scatta]

Thanks. I'll keep an eye out for a lone specimen, I think.

Personally, I'd bump the SG up to 1.012 if I were keeping a juvenile. It does seem the babies live in the sea and only the adults move into estuaries and freshwater. While I'd expect it would be fine at a lower SG, I can't guarantee that.

The reason I ask is because I also keep Orange Chromides and a Zig-Zag Eel in my brackish setup and they require a lower salinity don't they?

 

[nmonks]

The reason I ask is because I also keep Orange Chromides and a Zig-Zag Eel in my brackish setup and they require a lower salinity don't they?

Yes. In this case, if those are the two fish you have, I'd be looking at a very low SG system (10% seawater, or SG 1.003 will be fine for both). Spiny eels in particular do not like high salinities. It's a myth they need brackish water at all. There are some brackish water bagrids, but the ones I know best, like Mystus gulio, get a bit too big for your tank. Possibly reading around somewhere like Planet Catfish will yield some smaller species. I'm sure there are some -- catfish are very common in slightly brackish water. I just don't know the small species and whether they are traded or not.

Cheers,

Neale

 

[Scatta]

Yes. In this case, if those are the two fish you have, I'd be looking at a very low SG system (10% seawater, or SG 1.003 will be fine for both). Spiny eels in particular do not like high salinities.

Hmm, I may have to re-home my eel into my freshwater tank then.

I'm sure there are some -- catfish are very common in slightly brackish water. I just don't know the small species and whether they are traded or not.

That's fine. Thanks for your help!

Sorry to keep on about Plotosus lineatus, but I read that they have a lethal venomous spine on the dorsal fin. Is this an exaggeration or is this fish really that dangerous (although, it didn't actually state that it was lethal to humans, just lethal)?

 

[andywg]

P. lineatus does indeed carry a venom in its dorsal spines, though I do not recall hearing it is lethal. It is certainly not like the reef stonefish. I would expect it to be somewhat similar to a severe lionfish sting.

 

[nmonks]

Exactly so. These are more "Arrgh! I can't stand the pain" than actually keeling over and dying. That said, people do have allergic reactions to stings, and I'd definitely visit my local emergency room if I got stung. It's a good idea when keeping highly venomous animals like these to write down the Latin name and keep it somewhere handy. If you get stung and pass out, you want everyone in the house to know where that name is so they can quote it to the doctor. Once they have that name, then they can choose the right treatment.

Having said this, people have kept these fish for many years and never had problems. It isn't an aggressive fish and it only stings if man-handled. For predatory catfish, they're pretty easy going. We're not talking Hemibagrus wyckii here!

Cheers,

Neale

P. lineatus does indeed carry a venom in its dorsal spines, though I do not recall hearing it is lethal. It is certainly not like the reef stonefish. I would expect it to be somewhat similar to a severe lionfish sting.