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FAQs on the Blind Cave, Mexican Tetras, Genus Astyanax

Related Articles: Cardinal Tetras; A School of Beauty, Part II,  by Alesia Benedict, Characid Fishes

Related FAQs:  Cardinal Tetras, Characid/Tetra Fishes,


Blind Cave Tetra Compatibility     12/17/17
I'm thinking about getting back in the hobby again, and I'd like to keep blind cave tetras, since I have fairly hard water.
<Good choice. Their surface-living sibling, Astyanax mexicanus, is also available, and has the same requirements. Don't forget there are many South American tetras that handle hard water, particularly the X-Ray Tetra,
Pristella maxillaris. It's a gem of a fish, too.>
However, information seems to be mixed as to some things about them.
In particular, nowhere seems to agree as to whether they school like most tetras or not.
<Not as such, no. Singletons can be maintained successfully, though the species is looks good and is more fun in groups.>
Second of all, information also seems to vary as to whether they count as a mid-water swimmer or a bottom dweller.
<Midwater. Wild fish consume bat droppings, which apparently contain bits of undigested insects. So the fish dart about, responding to splashes at the surface, taking bites out of whatever they find. While they certainly will trawl the substrate, nibbling at food they find there, I wouldn't consider them catfish analogues.>
If they're a bottom-dweller, do they have a preferred substrate?
<Couldn't care less. Actual Mexican caves frequently contain sand and round pebbles, so this would be ideal. But I've seen beautiful tanks designed for these fish, using slate chippings at the bottom and vertical slate slabs to
create a cave-like habitat.>
Either way, I was thinking about using swordtails for a mid-to-surface-dwelling fish.
<Do-able. Similar in terms of size and personality. Might nip at the long tails of the male Swordtails, but shouldn't do if well fed and kept in a spacious aquarium.>
If the tetras count as a mid-water swimmer, are there any eel-like fish I could use as a bottom-dweller that are good for the conditions blind cave tetras and swordtails need?
<Horseface Loaches would be ideal, but they're quite big (up to 20cm/8 inches in some case) and MUST have a sandy substrate. I would recommend against Spiny Eels unless you had a sandy substrate, and I've seen Bichirs
nipped horribly by nippy fish, so I'd definitely not choose them either.
Cheers, Neale.>
Re: Blind Cave Tetra Compatibility     12/17/17

Thanks for the quick response. As far as the surface-dwelling Mexican tetra, I've never seen them for sale locally, but I might look into the X-ray tetras or some other South American hard water-tolerant species for a more traditional schooling fish possibility.
<Understood. The surface version is out there, but might be a special order. It's a rough and tumble fish, and just silvery with a bluish stripe, so isn't that popular.>
I assume Horseface loaches are a schooling species like most loaches?
<Nope. Mildly territorial, but often kept in small groups in large tanks. Mostly ignore each other.>
I have an empty 40 gallon breeder I'll most likely be using, and it seems like even three or four 8 inch long fish wouldn't leave much room to stock other fish, so that's probably out.
<Yes and no. There seem to be several species sold as the Horseface Loach, and it's pretty rare for any of them to get to full size. They aren't particularly fast growing, either. So you'd probably find the 40 gallon would be fine for at least a couple years for a small group, and perhaps indefinitely for a singleton.>
Would a spiny eel be acceptable if the substrate was a soft sandy one, or do you think they'd be subject to nipping from the tetras like a bichir?
<Possibly but be sure to have a Plan B just in case things went wrong.
Spiny Eels are difficult to keep alive at the best of times, and if you find the Spiny Eel is harassed in anyway, it will need to be rehomed. Cave Tetras aren't psycho fish, but they have evolved to bite anything that they come across, given their evolutionary background in a place where food is very limited and there are virtually no other fish living in those caves with them.>
If a spiny eel would be okay, would there be any particular advantage between the choices of a peacock spiny eel and a yellowtail one?
<Much of a muchness. Both Macrognathus pancalus and Macrognathus siamensis quite adaptable with regard to water chemistry, and get to much the same size.>
If that's not an option, I'll probably go for a school of some sort of Corydoras, unless there's some sort of bottom dweller suited for this tank native to Central America.
<Corydoras are sitting ducks for nippy fish. Been there, done that! Neale.>
Re: Blind Cave Tetra Compatibility     12/17/17

I don't want to take chances, so I guess I'll rule out the spiny eel. If Corydoras are a bad match for nippy fish, are there any other catfish that aren't sitting ducks for a nippy tetra and do well in the conditions blind cave tetras and swordtails need?
<Your standard issue Ancistrus species will be the obvious choices, handling relatively cool, fairly hard water perfectly well. So far as I know, there aren't any Mexican catfish in the trade, unfortunately. I mean, one or two might turn up occasionally, but nothing farmed or exported regularly. Cheers, Neale.>
Re: Blind Cave Tetra Compatibility    12/18/17

I did some looking around, and would either a school of upside-down catfish
<Probably fine.>
or a school of dojo loaches
<Nope; too peaceful, lack the nous to handle potentially difficult tankmates. Better off with something Botiine: Yoyo/Pakistani Loaches for example.>
fare okay with nippy fish in those conditions?
Information seems inconsistent as to how hard of water upside-down cats can do well in, and I'm not sure if the temperatures required for swordtails and blind cave tetras would be good for dojo loaches in the long term.
<Upside-down Cats are very adaptable. They're fine up to 20 degrees dH, pH 8. Don't like low temperatures though: 24 C/75 F probably the lowest I'd take them. Cheers, Neale.>

Blind in a cave, characin comp.  - 04/14/2006 Hi, <Hello> This is a wonderful site. <Thanks.> I have been in the  aquarium hobby for a while, and I figured I should introduce my younger sister to the wonderful world of fish keeping! <Good for both of you!> She has her heart set on Blind Cave Tetras (I think they are the ugliest fish out there! lol) and Silver Tip Tetras. Could she keep 6 of each in a 10 gal. aquarium? <This would be pushing it. Both species can be a little aggressive. I'm sure you'll make your sister aware of the importance of water quality/conditions for her pets but, specific to your question, I'd prefer to see her go with no more than three, or four, of each in this size of tank.> I would give her plenty of  plants from my tanks. <The Silver Tips would probably appreciate this. The Blind Caves won't really care.> She also wants to add driftwood, etc. <Keep in mind that decorations, plants and substrate affect the effective volume of the tank. Once you've set up your "10-gallon" tank the way that's pleasing to the eye, the effective volume left for your fish can be reduced by, perhaps, one quarter. In other words, your ten-gallon tank may be reduced, practically speaking, to about eight gallons. Maybe less. Something to keep in mind. ;)> I will also  give her a heater and filter, as well as a light. (It's her birthday) Is this an okay setup? Is there anything special we should know about them? <You'll be fine. Wish your sister a "Happy Birthday" from all of us at WWM.> Thanks in advance, Anthony <Tom> Thanks, I'll tell her to keep 3 of each! Thanks Again, Anthony <Any time, Anthony, and good luck. Tom>

Blind Cave Tetras and Algae Hello, love your site-- <Thanks for the kind words!> I'm planning a single species, blind cave tetras, 46 gal bowfront, and have a couple questions.  What would be a good filtration system?  I was considering using two Whisper 30-60 Advanced--the kind with the bio-sponges--or would I be better off with something else? <You may be able to get by with just one such filter.  Two may offer too much flow for the tetras.  You could certainly try it, and see how they do with the added water flow.  My own personal preference in power filters is with Marineland Penguin and Emperor filters, but the Whisper will do quite well for you, too.  Not to mention, the bonus of being able to remove carbon - the Marineland filters unfortunately do not offer that ability, unless you get creative with scissors.> Also, I say single species, but should I get something for algae control? <Well, that certainly depends on your tastes on lighting, in this case!  The tetras don't need a huge amount of light for obvious reasons.  Though, I don't see any problems with peaceful algae eaters, like Ancistrus Plecs or any of the various algae-eating shrimp.  Lots of options for you.  Sounds like a fun setup!> Thanks, Les <Sure thing.  Wishing you well,  -Sabrina>

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