Rio Orinoco Biotope (H. Osteocarus, P. Simulans)

[CassCats10 7]

I happened upon a rare group of cories from my lfs, they were ordered in as hoplisoma habrosum, but the store received ONLY hoplisoma osteocarus, which is only available as a by catch species and normally only a couple mixed as contaminants... not the entire batch being the mixed up species! Given the general rarity of the species kept globally, and the opportunity to get them again wouldn't pop up, I bought them. They're a rare dwarf species, not growing larger than 1.6 inches tops.

I set up my 10 gallon for them and opted to create a biotope from their natural range after doing more in depth research using GBIF . org to cross reference occurrences of this species with other species for plants and fish.

H. Osteocarus is found in Rio Atabapo, Rio Meta, and Rio Orinoco. Finding a tankmate that comes from these rivers that is also 1, easily found and 2, not too big/active for a 10 gallon was a little bit of a challenge, but found that where Rio Meta and Rio Orinoco meet, both Hoplisoma osteocarus and Paracheirodon simulans (green neon tetra) occur together.

My lfs was gracious enough to order me in a nice group of really handsome P simulans and I since added some water lettuce and a touch of guppy grass that is struggling with the dark water... all plants found in the same area. Pothos and zebra plant added up top, while not reported to exact location, both are at least found in the same country and I needed some root cover to mimic an edge of a river.

Because this is a very soft, acidic river, this tank is running at half distilled, so GH sits around 2°. I feel the tannins from the leaf litter, and the very soft water used along with a diet high in baby brine shrimp and daphnia, it has brought out more of the red in my P. simulans than expected, making them almost rival P. axelrodi (Cardinals) except the neon stripe extends right to the tail which rules out axelrodi and innesi.

Temperature sits at 78F given this region is a hot area.

I am going to attempt to spawn the corydoras, right now I am mimicking a dry season and will increase flow and increase distilled water to lower GH to 1° come wet season (May in Venezuela).

 

[CassCats10 7]

Video footage from last week

 

[anewbie]

View attachment 379190View attachment 379191

One small problem - having a large school of green neon tetra myself; those do not look like green neon tetra; rather they look distinctly like cardinal tetra which are of course much larger and more aggressive esp when it comes ot eggs and frys.

I see you mention this in your text but I believe there are different populations of cardinal with some variance esp between brazil and columbia. If they are not cardinal; they cannot be green neon tetra. I keep my green neon tetra in ec 20 ph somewhere down there water with some pygmy.

 

[CassCats10 7]

One small problem - having a large school of green neon tetra myself; those do not look like green neon tetra; rather they look distinctly like cardinal tetra which are of course much larger and more aggressive esp when it comes ot eggs and frys.

Except that the neon green/blue stripe ends exactly at the tail instead of the adipose fin.

Green neons differ from both Cardinals and normal neons by the neon stripe reaching the tail. Cardinals and neons the neon stripe ends at the adipose fin.

Was speaking with some Dutch friends of mine who keep green neons among other blackwater fish and they also found that theirs got the full red as well when kept in acidic blackwater setups, but also noted it very well could be a locale thing too.

 

[anewbie]

Except that the neon green/blue stripe ends exactly at the tail instead of the adipose fin.

Green neons differ from both Cardinals and normal neons by the neon stripe reaching the tail. Cardinals and neons the neon stripe ends at the adipose fin.

Was speaking with some Dutch friends of mine who keep green neons among other blackwater fish and they also found that theirs got the full red as well when kept in acidic blackwater setups, but also noted it very well could be a locale thing too.

Weird - i'll double check mine - their water is quite acidic i want to say mid 5s as the ec has sustained between 18 and 28 the past 2 years but i never seen their red line extend beyond hte middle range - i have 3 populations (well 3 groups from different sources but perhaps there is a catch location that has more red).

I took a look - i have to use a flashlight since the tank is so dark - the green line extends into the tail but the red line is very faint and does not go back very far - i wonder if there is sexual dimorphism or seasonal change or maybe your fish is an undescribed species lumped with green neon tetra. I've never seen the red so bold and full length before but in truth i've only owned green neon tetra a few times over the years.

Oh well not a bad fish if htey remain small.
---

I took a look at my cardinals and their red line extend all the way into the tail - they have red tails

 

[CassCats10 7]

Weird - i'll double check mine - their water is quite acidic i want to say mid 5s as the ec has sustained between 18 and 28 the past 2 years but i never seen their red line extend beyond hte middle range - i have 3 populations (well 3 groups from different sources but perhaps there is a catch location that has more red)

It definitely threw me for a loop as well, but we have definitely confirmed that they are 100% simulans. I did have to consult some folks because I even questioned the amount of red they have, but that is variable apparently, from none at all to full red. The neon stripe is what sets them apart besides some morphology differences you'd need to dissect them for lol.

It also can be impacted by the diet high in baby brine which has a high amount of beta carotene which can increase red tones. They get fed it 3x a week and they over-indulge like the little gluttons they are

 

[Innesfan32 16]

I had the same puzzled response as @anewbie. Could these possibly be that 4th yet undescribed Paracheirodon that Heiko claims to have discovered?

 

[anewbie]

View attachment 379230

It definitely threw me for a loop as well, but we have definitely confirmed that they are 100% simulans. I did have to consult some folks because I even questioned the amount of red they have, but that is variable apparently, from none at all to full red. The neon stripe is what sets them apart besides some morphology differences you'd need to dissect them for lol.

It also can be impacted by the diet high in baby brine which has a high amount of beta carotene which can increase red tones. They get fed it 3x a week and they over-indulge like the little gluttons they are

Any chance you can get a precise catch location so someone somewhere can do a real species analysis. In truth my green neon tetra look a lot like the above picture with a lot of weakness in the red line. It is true that some dwarf cichild pick up their red in the wild from carotene - we had a conversation about this on another forum about how some populations were getting a lot of carotene in their diet.

 

[CassCats10 7]

I had the same puzzled response as @anewbie. Could these possibly be that 4th yet undescribed Paracheirodon that Heiko claims to have discovered?

I had heard there was a potential other Paracheirodon but I could not find any documents describing the fish at all.

Any chance you can get a precise catch location so someone somewhere can do a real species analysis. In truth my green neon tetra look a lot like the above picture with a lot of weakness in the red line. It is true that some dwarf cichild pick up their red in the wild from carotene - we had a conversation about this on another forum about how some populations were getting a lot of carotene in their diet.

Unfortunately my lfs cannot get an exact catch location, best he can get is countries they were shipped from. I can double check with him and see what he can find out.

The reddest ones are my females, the males not as red. But some of the females the red isnt full either, but still very vivid.

Here's a male, red stops halfway.

 

[Innesfan32 16]

I had heard there was a potential other Paracheirodon but I could not find any documents describing the fish at all.

It's still undescribed--which is puzzling-- so there are no documents to read, however it is reported that preliminary investigation puts it closest to the Neon, P. innesi. Your most recent photos, with the red not fully covering the lower flank, certainly suggests that. I really think you may have the 4th Paracheirodon. I doubt beta carotene would be responsible for the color difference here. At the very least this is a 'cf' of one of the three known species.

 

[CassCats10 7]

It's still undescribed--which is puzzling-- so there are no documents to read, however it is reported that preliminary investigation puts it closest to the Neon, P. innesi. Your most recent photos, with the red not fully covering the lower flank, certainly suggests that. I really think you may have the 4th Paracheirodon. I doubt beta carotene would be responsible for the color difference here. At the very least this is a 'cf' of one of the three known species.

What I meant about "describing" is like what made him think it differed from the other species. His article didn't specify anything about how it looked, as far as I had read. I did happen upon that.

I am going to see if my Dutch friend can still contact a characin expert they were recently working with and see if they can pick his brain about these.

 

[anewbie]

It's still undescribed--which is puzzling-- so there are no documents to read, however it is reported that preliminary investigation puts it closest to the Neon, P. innesi. Your most recent photos, with the red not fully covering the lower flank, certainly suggests that. I really think you may have the 4th Paracheirodon. I doubt beta carotene would be responsible for the color difference here. At the very least this is a 'cf' of one of the three known species.

If they were tank raised could they be hybrid or slectivly bred ? If they are a 4th species it begs the question on adult size et all.

 

[CassCats10 7]

If they were tank raised could they be hybrid or slectivly bred ? If they are a 4th species it begs the question on adult size et all.

No, they are wild caught, that much we know.

Adult size, they have grown a little since I got them in January but have since stopped growing, so I think they're close to full size now, which is barely over an inch. Itty bitty guys.

 

[WhistlingBadger30 13]

Well, whatever your mystery tetras are, it is a wonderfully set up tank. I like that you have restrained yourself to only the two species (something I never can seem to pull off), which gives an elegantly simple feel to the environment. Beautifully done.

 

[CassCats10 7]

Well, whatever your mystery tetras are, it is a wonderfully set up tank. I like that you have restrained yourself to only the two species (something I never can seem to pull off), which gives an elegantly simple feel to the environment. Beautifully done.

It is only a 10 gallon and because I am going after a true blackwater environment, there is little plants to handle the extra bioload. So keeping it to 2 species is best.

Plus, this region is tricky to find species suitable for the tank size AND aren't impossible to find in the hobby. Or, aren't going to be a problem for the other fish. One contender were some dwarf marbled hatchetfish, but they aren't always easy to find and frankly I'm not particularly sold on their appearance anyways.

So I went with 12 of the tetras. Originally was 8 of the cories, but lost a couple in quarantine so now only 5. Hoping they breed so I can bump them to 10.

It's a quiet tank, but I am finding myself enjoying the quietness compared to some of my busier tanks. But the other tanks have way more plants so I can afford to stock them heavier.


If this were a larger setup, I'd have gone with a pair of wild German blue rams, quadruple the number of the tetras and about 20 of the cories, but alas, space is limited. I do feel though the tetras add some pop to the tank, because the cories blend in with the leaf litter with their light speckled pattern. Which, I find myself really liking to see. Once the leaves break down and have holes, the cories blend right into them.

Might be some doubles from earlier