Natural diet of cardinal tetra

[Stuporman]

Walker, I, 2004. The food spectrum of the cardinal - tetra (Paracheirodon axelrodi, Characidae) in its natural habitat. Acta Amazonica 34: 69-73.

Abstract

The cardinal tetra (Paracheirodon axelrodi) is the most intensively commercialized ornamental fish from the Rio Negro Basin (Amazonas State, Brasil). Analysis of the stomach and gut contents of fish caught in their natural habitats show conclusively that the cardinal is essentially a predator, feeding on the mesofauna that adheres to submerged litter, roots and waterplants. Microcrustacea and chironomid larvae (Diptera) were the most frequently ingested prey, while algae intake was relatively infrequent. It is argued that the relatively small size of the cardinals captured in their natural habitat is due to the annual migrations imposed by the inundation cycles, rather than to resource limitation, because it is known from earlier investigations of similar habitats, that these plant substrates are densely colonized by the aquatic mesofauna. Cardinals raised in captivity are larger and have higher rates of growth.

Pdf available here (http://acta.inpa.gov.br/Inteiros/PDF/v34n1a09.pdf).

[mad scientist]

thanks HH! :woot:

[Zealot]

Any reasons for the neon coloration? A distraction to predator?

[Stuporman]

Most blackwater fish have some red in them, because red appears black in the heavily attenuated light in blackwaters. The green/blue coloration in a number of species is presumably a visual cue for schooling fish.

[Zealot]

Most blackwater fish have some red in them, because red appears black in the heavily attenuated light in blackwaters. The green/blue coloration in a number of species is presumably a visual cue for schooling fish.

Sounds a bit stupid but is the red an indication that they need lots of oxygen? Like our blood has lots of red?

[Stuporman]

No, red appears black in conditions of very little light (e.g. in deep sea...that's why many deep sea shrimps are bright red). Same thing in blackwaters.

[budak]

But cavefishes have little or no pigment altogether.... is it because their habitats are reliably dark 100% of the time? Whereas deep sea shrimp/fish retain their camouflage pigmentation because they migrate to the surface at night (where there is some moonlight....)?? Is red a "common" (true or not) adaption because the pigmentation (carotenoids?) is biochemically easier (and therefore less energy consuming) to synthesise than black colours (melanophores?)???

And why is the sky blue???

[Stuporman]

And why is the sky blue???

http://www.why-is-the-sky-blue.org/why-is-the-sky-blue.html

[art]

Too much discovery channel :bangwall: lol

Is red a "common" (true or not) adaption because the pigmentation (carotenoids?) is biochemically easier (and therefore less energy consuming) to synthesise than black colours (melanophores?)???

Interested to know this too ... anyone ?

[Stuporman]

But cavefishes have little or no pigment altogether.... is it because their habitats are reliably dark 100% of the time? Whereas deep sea shrimp/fish retain their camouflage pigmentation because they migrate to the surface at night (where there is some moonlight....)?? Is red a "common" (true or not) adaption because the pigmentation (carotenoids?) is biochemically easier (and therefore less energy consuming) to synthesise than black colours (melanophores?)???

Actually, I should have clarified my point. At moderate depths, there is some light (but only in the blue-green end of the visible spectrum). Red appears black in this limited light. Same case in blackwaters.
At really abysmal depths, there is no light, and the organisms are mostly black. This is because the prey they feed on are bioluminescent, and it becomes necessary to mask this bioluminescence. Otherwise you'd advertise your presence and become prey yourself.
As for caves, it's pretty much the same situation as the abysmal depths. Except in this case, there is no problem with bioluminescent prey glowing through your gut, so there is no need to produce any pigmentation (it costs energy to produce pigmentation).

[Simplex]

And I've lernt a lot today....I love cavefish!

[budak]

The latest issue of TFH (which I browse in Kino since i find much of the mag rather crappy nowadays) has this article on cave fishes in some Hawaii cave (duh!). The author claims (he hasn't got photos) that species like Gambusia and Cyprinius carpio which were introduced to that area a century ago had produced blind forms (the caves also house a native cave mullet), and pondered whether this was a natural (albeit rather fast) development or due to some chemical influence.

[Stuporman]

I think the article concluded that the blind fishes were the result of a reaction to some chemical in the water.

[FishFan]

Interesting information. Thanks.

[art]

Good stuff :thumbsup:

[Simplex]

Can you please point me to where I can find that article of fish in Hawaii?

[Stuporman]

The November 2004 issue of Tropical Fish Hobbyist.

[MrTree]

And I've lernt a lot today....I love cavefish!

21 species of blind fish known in China, Yunnan got 7 species and Guangxi (not that far from where I am) got 9 species! Overnight bus can reach area with lots of caves. Wait for me to come back from Guangxi with some first! :p

[Stuporman]

Maurice showed me a picture of a cave Pterocryptis from Guangxi before. See you can catch or not.

[MrTree]

You want 500 g ? :p

You email me location lah...I got location of all these then I will find time chiong already. Got lobang to go.

[Simplex]

Don't catch too many lah!

Coming to Thailand at the end of the year right? You know what to do man :yumyum:

There is one cave in northern Thailand where 2 species of cave fishes live, one Schistura and one Neolisocheilus, a very neat place man. You will love it any fish lover will love that place. 5 hours from BKK!

[MrTree]

Haha, yeah, of course I won't..I think most of them are in the red list!!...don't even know when I have time to go as my kaki told me, need at least 1 week....

I wanted to go during X-mas period, but my gf might not be able to leave(it's the peak season in her industry)..So latest by Jan!!