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Crocodile toothpick fishies!

29K views 48 replies 14 participants last post by  Betta132 
#1 · (Edited)
I recently obtained five crocodile toothpick fish from my favorite LFS. The guy working there was actually their former owner, and he'd apparently been keeping them in a 2.5g with two lampeye killifish and a male betta. He'd been feeding mysis to the betta, but the other fish weren't getting fed- they were just eating random bugs.
The toothpickies are in my 29 Biocube, which is moderately planted and well on its way to being heavily planted. They're sharing it with various small schooling fish, most notable being a few ruby tetras who don't really show up at feeding time and are probably eating bugs. I haven't seen the little things since I put them in, but I'm not worried... The guy who used to own them said that he didn't see them often, and that was in a tiny tank. In fact, he thought he had only three until he took down the tank and found two more.
They really do look like crocodiles crossed with toothpicks.

Note: These are not the toothpick fish from the Amazon, the nasty parasitic ones that were in the news a while back. Those are catfish, and not a species that's kept in aquariums due to being parasitic. These are a harmless species, somewhat similar to sticklebacks, and they basically act like stubby pipefish. They hover around, eat small bugs (won't take prepared foods), and are totally harmless to anything short of near-microscopic bugs.



EDIT: CARE THINGY. This is based off of my research, as well as observation.
Indostomus crocodilus or paradoxus. Care is exactly the same, as far as the world knows. Crocs have black stripes on the fins of the males, paradoxus do not.
Crocodile toothpick fish, paradox fish, armored stickleback, and freshwater pipefish are some of their names.
They are more closely related to sticklebacks than pipefish, but they act like pipefish.
Maximum size: 3-4 cm or so, males maybe a bit smaller. Very small, very thin, low bio-load.
Food: Very small things. Could possibly be weaned onto Cyclop-Eeze, but can most likely feed themselves from bugs in plants in a well-established tank. Micro-worms are a suggested food that I think would work well.
Compatibility: Not particularly afraid of active fish like emerald eye rasboras, don't care about others. Probably safe with anything that won't eat them. Will also be safe with any cherry shrimp past newborn stage- they're very tiny and have small mouths.
According to the former owner, they prefer to have others of their kind around, like ottos. That's why I got all five, so none would be left with too few companions. From what I've seen, the males may be mildly territorial when it comes to nice spots.
Breeding: Not sure. Egg-layers, I think, as males do not have gonopodiums. Probably best to keep them in a heavily planted tank and just let them do their thing. The only breeding instance I've read about was basically a bunch of them in a planted tank on their own, so it's somewhat possible they can change gender.
Gender determination: Male crocs' will have black stripes on their fins. Females are slightly larger and fatter in both species.
Notes:

They hover around a lot and use any nearby object as 'down', so they can be seen swimming vertically. They're very slow, methodical feeders that kind of just drift around... I'd say they need special feeding, except that they feed themselves.

Do not keep in a non-planted tank. Also, probably best to give them some oak leaves in hopes of growing bugs.

You will NOT see them often. They aren't skittish, just kind of reclusive. They prefer to hang around in the background and will only sometimes drift out to look around.

They are simply not afraid of most fish. I watched one sit in the middle of an emerald rasbora swarm for a few minutes, and it didn't seem to care that it was surrounded by streaks of chaos that were bigger than it.

They're also very curious about shrimp, but they aren't able to eat an adult one or even bother it very much.

Sort of rare in the hobby, as far as I'm aware. Grab them if they turn up.

They like to swim with their back pressed to the underside of a stick. Makes them look like a piece of bark.

They should NOT be kept without wood or sticks or similar. It's their favorite place to be, as far as I can tell.

They can actually move very fast when startled, despite their tiny fins.

The tail is mostly used for steering, but the fin can be used for one strong push if they need to dart to cover.

They have a pair of tiny fins in their stomach area that they often rest on.

Males tend to become more active if they see each other. Not sure why. It doesn't look aggressive...

Males do not have gonopodiums, as far as I can see, so I doubt they're livebearers.

They don't seem to school or anything. Their habit of being near each other is likely due simply to them liking certain spots- such as all hanging out under driftwood.

They aren't a huge fan of bright lights but will venture out into the open now and then to investigate. A mild amount of tannins should help make them come out a bit more; I'd suggest a few oak leaves.

They're curious and seem intelligent- sort of remind me of bettas in some ways.

Upon noticing somebody watching them, they often pause to stare at their watcher for a minute or two.

They like to sit still and pretend to be twigs.

They aren't particularly bothered by other fish. They do avoid large clumps of activity, but they don't look scared... They just slowly circumvent the overly active area, eyes on the activity, and proceed on their way once they get past the chaos.

They don't like being approached from behind by larger fish and will quickly swim a few inches away before continuing.

Oddly, being run into by an emerald eye rasbora (fast, about as long as the 'crocs but three times thicker) doesn't bother them beyond making them race away a few inches and put something between them and the offender- at least, from what I saw. Little guy didn't even look upset, just kind of annoyed.
 
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#4 ·
Technically they aren't pipefish, they just act like them.
There are freshwater pipefish, one species, in fact.

I just saw another one today, drifting lazily around.

Here's all I have on them from research and observation.
Maximum size: 3 cm or so, males maybe a bit smaller. Very small, very thin, low bio-load.
Food: Very small things. Could possibly be weaned onto Cyclop-Eeze, but can usually feed themselves from bugs in plants.
Compatibility: Not afraid of active fish like emerald eye rasboras, don't care about others. Probably safe with anything that won't eat them. Will also be safe with any cherry shrimp past newborn stage- they're very tiny and have small mouths.
According to the former owner, they prefer to have others of their kind around, like ottos. That's why I got all five, so none would be left with too few companions.
Breeding: Not sure. Egg-layers, I think. Probably best to keep them in a heavily planted tank and just let them do their thing.
Gender determination: Males (sometimes) smaller and skinnier than females. I have two males, one female, and two indeterminate ones that are in-between. It's possible they can change gender- no one's really sure. The only breeding instance I've read about was basically a bunch of them in a planted tank on their own, so we have no proof they can't change gender like many fish can.
Other stuff: They hover around a lot and use any nearby object as 'down', so they can be seen swimming vertically. They're very slow, methodical feeders that kind of just drift around... I'd say they need special feeding, except that they feed themselves.
Do not keep in a non-planted tank. Also, probably best to give them some oak leaves in hopes of growing bugs.
You will NOT see them often. They aren't skittish, just kind of reclusive. They prefer to hang around in the background and will only sometimes drift out to look around.
They are simply not afraid of most fish. I watched one sit in the middle of an emerald rasbora swarm for a few minutes, and it didn't seem to care that it was surrounded by streaks of chaos that were bigger than it. They're also very curious about shrimp, but they aren't able to eat an adult one or even bother it very much.
Very rare in the hobby, as far as I'm aware. Grab them if they turn up.

Down at the bottom we have a picture of all of them in the bag, and also the only good picture I have of one while it's in my tank. It's demonstrating that anything it chooses is the floor.

If you get the chance and have a planted tank with fish small enough to not eat them, buy these guys. You may not see them much, but they have such a low bio-load it's okay. Plus, that just makes it more awesome when they do come out.
 

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#6 · (Edited)
They most definitely are.

And I've just confirmed something else about them: They like to be under things. Two of mine are currently hanging out under a piece of driftwood, upside down with their bellies a millimeter away from the wood, and they were doing similar things in the display tank. Interestingly, being in a display tank didn't seem to bother them at all... They were just doing their thing.
 
#8 · (Edited)
They do look a lot like tiny whiptail cats, I suppose, but they definitely aren't. They have pipefish heads, for one, and they're much rounder. Whiptails are kind of flattened if you look at them from the side.
 
#9 ·
I think I can safely say that these guys are not suited for tanks that aren't tiny. I just don't see them at all.
Perhaps a better setup would be a bunch of leaf litter at the bottom and a piece of driftwood, maybe a plant or two. Loads of leaf litter = loads of bugs, but that would mean they might be out more. They didn't seem too timid in the display tank- which is interesting given that many fish are -so I think they'd be okay with the much sparser environment.
 
#10 ·
Saw two of them today, and one was the largest one. That probably bodes well.
One just came drifting out to spend some time sailing around the bottom right out in the open. He's my new phone wallpaper. Little thing wasn't scared at all... In fact, I put my finger up to the glass a quarter inch away from him and he just followed it around with his eyes. They're remarkably bold for such reclusive, tiny little things.
 
#11 ·
Armoured stickleback is what I see them sold as most often. I had a hard time getting mine to eat anything other than live foods when I had them years ago. They have tiny little mouths. Having a well established, mature planted tank will help as it can provide an additional food source from the micro fauna in there but will still need to provide them with live foods from my experience.

They could be either Indostomus paradoxus or Indostomus crocodilus.
 
#13 ·
The ones I'm seeing are still plump and happy. I think they're good...
The former owner had them in a 2.5g and wasn't feeding them. He gave his betta mysis and that was it. I think they'll be okay, but I am offering them foods now and then to see if they want any. They won't take anything.
They're eating at something I can't see, definitely. I see them picking at things, and even when it's right on the glass I can't see what it is. Must be something tiny.

How would one tell the difference between the two? The pictures I found seem to indicate that crocodilus have larger back spines...
 
#15 ·
Hmm... Micro worms? I could try that- bet I can get a culture. If anything, the tank would love them. I know they can survive for a while underwater, maybe I'll just put a bunch in the back and see if anybody wants them.

I can't vouch for coloring on the fins, they're a bit reclusive. I'll have to try next time I see one.
Any way to sex them? I'm guessing that my two smallest are males and my bigger fat one is a female. Not sure about the two in-between ones.

They're in a 29g but tend to stick around the back of the tank, possibly because they prefer the shadows.
Do you think they're shy or just a bit reclusive? They don't seem afraid or anything when drifting around in the open, but they stay in the back a lot. I see them perching on the underside of the wood, so I think they like shadows. They appear to love my hornwort clump, too.
I'm working on growing a moss/hornwort clump area for critters to breed in. I bet they'll love it.
 
#16 ·
They do prefer to hide under branches as that is what they would do in the wild. You can also add leaf litter. They are a shy and reclusive fish but as long as they are getting their dietary needs met you should be good. Any floaters will also make them feel more at home and diffuse the light. I had mine in a 10 gal. tank and the bottom was covered with leaves and they always were hiding under them or on the underside of wood. You could also put some PVC pipe in there for them to hide in but I prefer to keep it as natural as possible so the wood and leaf litter did just fine. I just noticed the other day that a new sponsor here, Aquarium CO-OP has these listed for sale. I may have to try them again in the future as I haven't seen them at my LFS for over 9 years. Probably because most people wouldn't even notice them in their tanks. Keep this thread updated as I would like to know how they do for you.

Edit: Here's a cool video of one eating I found on YouTube

https://m.youtube.com/watch?v=KtmXLPDhNtU
 
#17 ·
Lots of duckweed and hornwort up top, some oak leaves in the bottom, also some twigs. I think I'll add more leaves, but I gotta find some that don't release buckets of tannins. Maybe pecans... Lots of veins and places for buggies.
I may add a few more sticks for them. Hopefully that'll make 'em come out more just to hover under the sticks.
I hardly see them, but I wouldn't get rid of them if I could. They have so little bio-load that the little I see of them is worth it.
I'll update now and then with anything new or just continued success stories, and with the occasional cutie photo.

I really hope I can coax them into breeding for me... I doubt it'll happen, but maybe if I'm really lucky.
 
#18 · (Edited)
Saw two of them today. One was a bit larger, and the small one was under an overhang. Larger one went under the overhang, small one fled. Not sure if it was territorial or what.

The males appear to have blackish stripes across the rays in their fins, but the membrane is clear. Does that tell anyone what kind they are?

Edit:
Confirmed! Indostomus crocodilus, judging by the markings on the fins of the two I know are males.
http://www.seriouslyfish.com/species/indostomus-crocodilus/

Anyone know if a lack of the stripes means it's a female? These are from the same source, so presumably they're all the same.
 
#19 ·
If they are indeed Indostomus crocodilus then the males will have wide elongated pelvic fins that curve and the females pelvic fins are straight and not as wide.
 
#21 ·
That's usually the case. The males in Indostomus crocodilus will have dark brown or black lines in their dorsal and anal fins.
 
#22 ·
Good... That should help me figure out if I have any females. Hoping I do... I wanna see if they'll breed for me.

Males appear to be mildly territorial when it comes to nice spots. One of mine puffed up a bit and kind of looked display-ish towards a smaller male who was under a nice dark overhang. Tiny one retreated but didn't seem particularly mad.
 
#23 ·
One of these is a contrast shot against the Biocube lid when it fell in. Very good picture of a little fella.
Other two pics are just cute things, including one showing what he does when he's nervous about a phone or similar; rests down on the bottom and just sits still.

Not sure if that video worked or not. Let's see.
It's just a video of one little fella swimming around.
No, he didn't get nipped by that one rasbora- it just bumped into him. They do that now and then, bump into others who suddenly appear.
 

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#24 ·
To sum up some of the things I've learned about these guys, especially today:

They like to swim with their back pressed to the underside of a stick. Makes them look like a piece of bark.

They should NOT be kept without wood or sticks or similar. It's their favorite place to be, as far as I can tell.

They can actually move very fast when startled, despite their tiny fins.

The tail is mostly used for steering, but the fin can be used for one strong push if they need to dart to cover.

They have a pair of tiny fins in their stomach area that they often rest on.

Males tend to become more active if they see each other. Not sure why. It doesn't look aggressive...

Males do not have gonopodiums, as far as I can see, so I doubt they're livebearers.

They don't seem to school or anything. Their habit of being near each other is likely due simply to them liking certain spots- such as all hanging out under driftwood.

They aren't a huge fan of bright lights but will venture out into the open now and then to investigate.

They're curious and seem very smart.

Upon noticing somebody watching them, they often pause to stare at their watcher for a minute or two.

They like to sit still and pretend to be twigs.

They aren't particularly bothered by other fish. They do avoid large clumps of activity, but they don't look scared... They just slowly circumvent the overly active area, eyes on the activity, and proceed on their way once they get past the chaos.

They don't like being approached from behind by larger fish and will quickly swim a few inches away before continuing.

Oddly, being run into by an emerald eye rasbora (fast, about as long as the 'crocs but three times thicker) doesn't bother them beyond making them race away a few inches and put something between them and the offender- at least, from what I saw. Little guy didn't even look upset, just kind of annoyed.
 
#39 · (Edited)
Hey, that's me. Heh.
I'm a year late but I just got ahold of a few more of these fishies (I.crocs supposedly) with the hopes of breeding them again. I hope you don't mind if I post in your thread? Please let me know.

To answer your question, back then I kept them in a wild sand tank as in it was literally in a north facing window getting morning sunlight and most of the plant growth was riparian with a mess of roots underwater. Minimal care. I topped off the water, threw in ketapang leaves or any browned plant leaves lying around the house, occasionally fed brine shrimp (I use a hatchery dish), daphnia and scuds (when I had them), greenwater/infusoria (window cultures). I had microworms on hand back then but I don't recall if I fed those regularly. I must have but I don't have the sense that I did... odd. I can agree that the toothpicks like it dark so I had a big piece of overhanging driftwood pretty much blocking any direct sunlight and many random pieces of binchotan bamboo charcoal tubes for their houses. lol PVC pipes also do the trick, I've heard.

I did observe that the females were hugely fat when the fry appeared (eggs or cannibalism, I will never know...). I will try to track down those pictures.

This happened in the winter, in February, which is odd considering that there was the cold from the window affecting the tank temperatures. Maybe the breeze mocked their natural monsoon season (I believe they are native to Burma/India), when the cold/dry season comes in? I have no idea.

pH was slightly acidic, brown with tannins
TDS was soft 40-120ppm
temp was set at 70-80degF

I did not get the opportunity of raising the fry since I left overseas soon after they hatched and by the time I returned, there were none remaining despite my extra precautions of adding moss and brown leaves. Later that year, my breeding stock sickened until I was down to one adult survivor. That tank has been torn down.

Surprisingly this survivor is still fat and alive and ornery as ever. I added three youngsters recently (.75"), and am looking for more, in the hopes of seeing them breed again. Looks like Spring/Summer is the best time to look for these fish. Wish me luck. I can't sex these guys for my life. I can't even tell if they're crocodilus or paradoxus.

Here's pics of the fry, that's sand under it:


And for size, that's Najas grass:


macro pics from dasob85:
 
#27 ·
I've just found one dead :(
The smallest one... No marks on it aside from missing eyeballs and an apparent missing gill cover. I blame the baby MTS for those, as I found one chewing on its belly. Its belly doesn't look sunken in or anything, so I don't think it starved...
My guess would be perhaps old age? I was told that they grew in the time that the former owner had them, but I'm assuming they were juveniles or young adults when captured. I doubt anybody caught a tiny baby toothpick out of the wild... They're simply too small. I'll have to ask how long the former owner had 'em.
 
#29 ·
They are pretty inflexible little fish, they just motor around with their fins. They can bend their tails if they need to, but they usually don't... Like twig catfish.
I don't have the space to set up another tank, and plus they need a very established tank so they can eat the little bugs. Also, not sure if I could even find them to move them!
 
#30 ·
Was starting to get concerned about the rest, as I haven't seen them in a while, but one came out today. He looks healthy, at least. He's darker colored than I remember, though, and the two little fins on his underside are black along the bases and leading edges. The coloring is even, so I don't think it's some kind of illness... I bet it's a change in response to the black sand in the tank. Many of the more reclusive fish I've seen can change colors to some extent.
Two of the emerald eyes took nips at his tail as he swam up through the school, but he didn't seem too bothered... He darted a couple of inches, then resumed his leisurely swimming. These fish are really not scared of things, so I'm not sure why they spend so much time hiding. Not afraid of the boisterous rasboras, not afraid of me outside the tank, not afraid of my hand IN the tank adjusting things... I don't get it.
 
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