Shovelnose species.

[johnnyev]

In my LFS they have a small 3" shovel nose. Although it looks a little like the Sorubim lima i have, there are a couple of quite pronounced differences. Firstly the tail on the small cat in the shop is very forked, it has a much broader, flatter snout & its markings are more spotted, rather than having the dark horizontal bands that run along the flanks of the Sorubim i presently have. Could it be a hybrid with a Tiger shovelnose do you think? Sorry i know its a difficultquestion to answer without pics. Anyone have any info at all?

[johnnyev]

Looking through the cat-elog it looks like Pseudoplatystoma sp. hybrid(3) could be a very likely candidate. If so what are the species involved?

[Shane]

When talking about hybrids like

Pseudoplatystoma sp_hybrid(3)

it is really hard to say what species are involved. We could make some (educated) guesses but they would be just that. There might be some literature out there for the aquaculture industry on Pimelodid hybrids, so that might be a good starting point if you are really interested in trying to nail down an answer.
You may also want to check out Lee's article on the topic.
http://www.planetcatfish.com/shanesworl ... cle_id=180
-Shane

[Viktor Jarikov]

This is the commonly sold TSN everywhere in the US. I have never seen a different baby fish under the TSN label in any LFSs (barring obviously wrong labels).

[johnnyev]

Thanks Shane, Viktor.
I was thinking it looked a little like TSN, but as i'm not a fan of hybrids, wasn't too sure.

[Viktor Jarikov]

I can only say what I've read here. To sum it up (please, any one correct me if I am wrong). Some experts, who know what baby TSNs look like, believe that this strange-looking baby TSN is unlikely to be a purebred (hence it is classified as a hybrid in the Cat-eLog). The wide white lateral band is non-TSN-ish and leads some to hypothesize that perhaps TSN are interbred with something like Sorumichthys planiceps, who do have such a white band. Others say the SA farmers have huge ponds with all kinds of TSNs and who knows what else in those ponds and let them breed and interbreed as they please. 99% of the product goes to food. 1% or so to ornamental fish trade.

[sidguppy]

and who knows what else in those ponds and let them breed and interbreed as they please

unfortunately, no

it goes quite differently

even when mixed, these catfish are highly unlikely to hybridise

not only do they live together in the wild, where they could crossbreed, but don't
second; these fish need to migrate to spawn, and henxce dont breed by themselves when kept in a pond
like the syno's, they are injected with hormones and then squeezed.
the eggs and semen are mixed and thus the hybrids are created deliberately

why do they mix them and not breed true, one might think?

it's not because those who inject the fish can't spot the difference between a Red tail and a TSN

it is done on purpose and it is done because there is a phenomena called "hybrid vigor".

most hybrids grow faster and also grow bigger and often are much tougher than either parent species.

the fast growth and bigger size means more (edible) fish for the money/time/effort involved than when breeding true.

the toughness is needed when kept in astronomical numbers in a pond

espexcially pseudoplatystoma needs quite a bit of current and oxygen to flourish; to keepn it in a pond in high numbers without the massive waterchanges and filtration the big-tank-keepers do would quickly lead to a high stinking pile of dead TSN's.

less fragile, but still more fragile than the hybrids is the Red Tail.

so the hybrid can withstand much neglect, loss of oxygen and cramped space.
much more than the TSn or the Red Tail

these things don't just happen when they mix the parental fish.

the big Pim hybrids are not accidentically made, but created on purpose

[Viktor Jarikov]

So, to go back to the topic, what do you think Pseudoplatistoma hybrid 3 is?
I don't think it involves an RTC.

[sidguppy]

looks a bit like Pseudoplatystoma x Sorubim to me, but it could be Pseudoplatystoma x Sorubimichthys as well; both Sorubim and Sorubimichthys have the white lateral stripe

personally i tend to think one of the parents is Sorubimichthys rather than Sorubim.
but only DNA research or an explanation from those who create these mutts will solve this

[johnnyev]

Cheers Viktor.
Sid that is really interesting info, thanks. Looking at the two images in the cat-e log, Pseudoplatystoma x Sorubimichthys seems the closest match, although as Sid said, without DNA i suppose we'll never know for sure.

[Jools]

It could be anything, but why hyridise a food fish (

Pseudoplatystoma

) with a smaller fish (

Sorubim

)? My opinion is that these things are runts, deformed fishes that occur sometimes with careless raising of batches of artificially fertilised fish. I watched a tiger shovelnose grow up from a 5cm fish to sub-adult and, for me, they look like this as they grow (less the bent head we see in sp(3)).

This is also interesting and mentions (as an aside) natural sprint (31km) spawning.

Jools

[Shane]

it is done on purpose and it is done because there is a phenomena called "hybrid vigor".

There actually is a "positive" reason as well. These hybrids are infertile so escapees from aquaculture farms can not accidently become an unintended negative impact on their environment. This is really a growing reason for hybridization among food fishes. Some places will not permit the production of fertile fishes for aquaculture purposes.

-Shane