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Low pH blackwater tanks for Parosphromenus

brhau

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Hi all,
After taking a short break, I've started up my tanks again and I'd like to try building up a stable population of one of the described Parosphromenus species. I've kept softwater fish before, but never blackwater. So far, I have 4 tanks that have been running for about 6 weeks, 5 of those weeks with leaf litter, and about 4 weeks with plants. The surviving plants have really started to grow in the last 2 weeks, so I think I'm ready to add fish as soon as I can source the ones I want.

Here's my approximate stocking plan:
10-gallon tank: founder colony of 6 - 8 specimens, depending on species.
5-gallon tank: reserve for a breeding pair
15-gallon tank: growout
20-gallon long: display/community + growout. I plan to stock about 15 Boraras brigittae and hopefully 8 Hemirhamphodon tengah. I've tried to order the H. tengah already, but unfortunately the importer could not keep them alive. They're hard to get in the States, but I'll keep looking.
2.5-gallon: breeder or hospital tank

Water parameters:
Temperature: 23C for the paros tanks, 25C for the tengah
GH: 0
KH: 0
EC: about 50 us/cm
pH: 4.5 - 5

It's predictably difficult to stably maintain a low pH in these tanks. The resting pH of my RODI water is around 5.5. I can lower the pH to 4.5 by adding 2 drops of 1M sulfuric acid per gallon of RODI. However, the pH always drifts up due to the carbonate-carbonic acid equilibrium. To overcome this, I first add an excess of acid (for example, over 1 ml of acid per 10 gallons of aquarium volume) to neutralize the carbonate and move the equilibrium point lower. Once this is achieved, I add roughly 25% of that with each weekly water change to hold the pH between 4.5 and 4.8. The exact amounts are determined empirically and vary slightly by tank. Notes:
  1. I've ordered some 10% phosphoric acid to use in rotation with sulfuric acid. The residual ions of these acids are both macronutrients for my plants, so hopefully this will lower my EC a bit and benefit the plants, which otherwise don't get any added fertilizer.
  2. My 20-gallon display tank is stubborn, and the pH rises much more quickly to a higher equilibrium. The only material difference between this tank and the others is the presence of a very large azalea root. I think the mistake I made here was waterlogging it in my RODI reject water. My tap water contains NaOH, so it seems I've added a sink of it that's continuing to neutralize my acid. I assume it will eventually exhaust. I do frequent, small water changes in the 20-gallon and the 5-gallon, since those have inverts in them. For the other tanks, I can still add the acid directly, only changing water occasionally to lower the EC.
The inverts:
The 20-gallon tank theoretically houses 8 Tangerine tigers. They're smaller than breeding size, so in a crowded tank it's hard to confirm that they're still alive. I did see one last swimming about last week.
The 5-gallon tank has about 40 adult Asellus aquaticus. When I received them, there were about 50 tiny juveniles that I dumped in the tank as well. I have seen a few of those, though again they're hard to find amongst all the leaf litter.
Both of these species are prolific breeders, so I hope to distribute them to all the tanks eventually.

Plants:
I've tried a number of plants I thought would survive in blackwater and that might be appropriate for the environments. It was rough going in the beginning, as they all experienced some form of shock moving from whatever lush farm they came from to my blackwater tanks. But a few are really starting to settle in, albeit with smaller leaves, etc.

Successes (consistent new growth):
Salvinia natans
Salvinia auriculata
Salvinia minima
Ceratopteris thalictroide
s - Oddly, this is the first time I've gotten this to grow. Who knew I just needed to try blackwater?

Failures:
Pistia stratiotes - These melted right away. I don't think I'll try them again, as I don't think I ever use enough light to keep them happy. I end up with a million tiny leaves that are hard to collect and throw away.
Ceratophyllum demersum - I actually did get this to grow, but I don't like the extent to which it routinely sheds needles. That's not the type of bioload I want.
Azolla filiculoides - I naively ordered some of these not knowing how small the leaves are. I had duckweed flashbacks and decided not to use it.

Pushes:
Hydrocotyle leucocephala - It's growing, but shows clear deficiencies. It's also from the wrong continent (as a few of these plants are) but I added it in the beginning when nothing else would grow.
Süsswassertang - It looks fine, but I don't know that it would ever tell me if it's unhappy.
Vesicularia montagnei - It looks fine, but I don't know that it would ever tell me if it's unhappy.
Microsorum pteropus (Trident) - Grows too slow for me to tell.
Bucephelandra spp. - Grows too slow for me to tell.

Still trying:
Phyllanthus fluitans - These didn't survive the initial shock, but I'm going to try them again. There are a couple leaves that look healthy still, and the tank has matured a lot since I first added this.
Rotala H'ra - Just got these stems and haven't added to a tank yet.

Here's what the display tank looks like now. The other tanks aren't scaped or anything, they're really just holding tanks for plants. Will update you as things progress!

Cheers

IMG_2557.jpg
 
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brhau

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The tanks have their first vertebrates! I've added 17 Boraras brigittae to the 20g display tank. The water they came in was basically liquid cement: EC of 700 us and a pH of 7.4. Acclimating at 2 drops/second, it took 7 hours (!) to get the EC below 100 us and the pH below 5.5. One fish didn't make it through acclimation (I ordered 18, expecting DOAs). That one didn't look well quite early on, though. The others have looked pretty healthy.

The fish are settling in OK. A handful of them still surfs the glass at the left wall occasionally, but the rest are occupying all areas of the tank and picking at the mulm. The larger fish are showing some nice color (pictures below). They're taking BBS twice daily (I need to lighten the feedings, as their bellies are looking slightly chunky). I ordered Northfin fry starter, which is an excellent food of freeze-dried krill that stinks to high heaven. Not sure if I'll ever get that smell out of my cabinet. Of course, they just spit it out. I've started mixing in some crushed Bug Bites Betta Formula, and they will eat that.

No sign of the tangerine tigers in a while. In my experience, this doesn't mean they aren't there, but if they are, they're keeping themselves rather sparse.

5-gallon tank: The juvenile Asellus, which basically looked like flecks of white dust when I added them to the tank, have darkened slightly and grown quite a bit. The largest I can see in the tank is about 3mm long. I believe they reach maturity on the order of months. The adults are quite friendly with one another, so I expect this to be a very productive tank until fish are added.

Coming soon: I've located some Hemirhamphodon tengah! I plan to import them, along with Parosphromenus phoenicurus in early June. I have grindal worms and vinegar eels going, but I'll soon start a moina culture and some springtails for the tengah.

Cheers

_DSC0341.jpg
_DSC0362.jpg
 

brhau

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Thanks! H. tengah are sympatric with Parosphromenus in the peat swamps of Borneo. I hadn't heard of them until I started researching the paros, and I'm obsessed. They're quite difficult to come by here. I missed two stocks of them; one sold out, and the other I paid for but the vendor canceled the order. Both sellers said it had been years since they had them last, so I felt it was worth the effort to import.
 

tigertim

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I've had Parosphromenus living quite happily in water of kh 3 gh 4 ph7.5 for years, not breeding though, you should add whiteworms to the food list, similiar culture to grindal worms.
I would definetly add some Cryptocoryne plants as being suitable especially as they come from the same locations.
 

brhau

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I've had Parosphromenus living quite happily in water of kh 3 gh 4 ph7.5 for years, not breeding though, you should add whiteworms to the food list, similiar culture to grindal worms.
I would definetly add some Cryptocoryne plants as being suitable especially as they come from the same locations.
Great to hear! Which species are you keeping? My intention is to breed, which would not be possible with those water parameters. I know some breeders will omit water changes to allow the pH to drift up, which slows breeding. May I ask if you're treating the water with UV? pH 7.5 is permissive for certain bacteria that can't survive at low pH. That's the main reason I'm keeping the pH low-- to avoid infection, as true blackwater fishes haven't adapted immunity to those.

Whiteworms are certainly good for my climate, as my garage typically stays below 20C. I may try it, though they're a bit large for the Boraras and the Hemirhamphodon,
I adore crypts, but I'm not sure it's feasible for me. The ones endemic to Malaysia live in areas of higher water flow and nutrient content than is desirable for the paros. They can grow emersed, however, though my tanks aren't configured for that. The Sri Lankan species commonly available here can't survive low-nutrient water. Also, my substrate is only about 1 - 2 cm thick-- enough to act as a substrate for bacteria and archaea, but likely insufficient for rooted plants.

Cheers
 

tigertim

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Great to hear! Which species are you keeping? My intention is to breed, which would not be possible with those water parameters. I know some breeders will omit water changes to allow the pH to drift up, which slows breeding. May I ask if you're treating the water with UV? pH 7.5 is permissive for certain bacteria that can't survive at low pH. That's the main reason I'm keeping the pH low-- to avoid infection, as true blackwater fishes haven't adapted immunity to those.

Whiteworms are certainly good for my climate, as my garage typically stays below 20C. I may try it, though they're a bit large for the Boraras and the Hemirhamphodon,
I adore crypts, but I'm not sure it's feasible for me. The ones endemic to Malaysia live in areas of higher water flow and nutrient content than is desirable for the paros. They can grow emersed, however, though my tanks aren't configured for that. The Sri Lankan species commonly available here can't survive low-nutrient water. Also, my substrate is only about 1 - 2 cm thick-- enough to act as a substrate for bacteria and archaea, but likely insufficient for rooted plants.

Cheers
parosphromenus bintan to start with then i later added some cf. deissneri,
I use Cattapa leaves re infection but never had any issues for normal keeping and no uv, i think your possibly over thinking things, clean soft water regardless of ph and plenty of live foods are the key imho
Have you looked up the Parosphromenus Project much more info in here in regards to breeding.
 

brhau

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Have you looked up the Parosphromenus Project much more info in here in regards to breeding.
Hi, thanks. Yes, this is where I’m getting my information. Those forums are largely inactive now, but several of the members are active on their Facebook page.

Cheers
 

brhau

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Sadly, I've decided not to import the Hemirhamphodon tengah. They're collected in Borneo, and with the lengthy trip to Indonesia, the seller says this last batch was not in good shape. He's getting more from the hunter next week, but they don't appear to travel well. It seems risky to buy a handful and hope they survive a 7-10 day trip to the States. So I'm focusing on getting 4 pairs of Parosphromenus phoenicurus. I should be able to get them on an early June shipment.

The vertebrates: Of the 17 Boraras, I don't tend to see all of them at once. I've never kept this many fish in a single shoal before, but I'm guessing this is typical in a heavily structured tank. Usually, 10 - 12 of them are really active during feeding time, and another 2 or 3 show up at the end. I was able to see 16 of them at the last water change, however.

The food pets: About a month in, the grindal worm culture is really starting to come around. I'm learning what not to do (for example, they don't like acidic tank water) and what to do (more water changes than I thought and higher stacks of scrubber pads for more surface area). The vinegar eels are growing as expected, so I should have plenty available in the event of fry. I should be getting my Chlorella vulgaris culture soon, so I can start making green water for a moina hatch.

The plants:
Salvinia - Of the 3 species I had going, I've consolidated to just S. natans. In my conditions, it grows in well spaced, ordered rows. This makes it much easier to trim than S. minima, for example, which grows heavily overlapped in my hands.

Phyllanthus fluitans - As I'd hoped, hese are doing a lot better on the second go around. They really like my 20 long, probably because there's a lot of surface area with low (or no) flow.

Bucephalandra spp - These aren't doing great. I avoided planting these in the 20 long, because when they arrived I had <quite a bit of biofilm on the azalea root>. So I glued them to other bits of wood and let them sit in other tanks. Silly mistake, as two of those pieces of wood are now covered in biofilm, which I'm constantly pulling off the plants to keep them from suffocating. In the meantime, the fuzz on my azalea root has mostly gone away. I do have some buce cuttings glued to a piece of Malaysian driftwood that isn't fuzzy at all. Those are even in a higher nutrient tank (my son's Betta tank) and they aren't happy either. A bit disappointing, since these plants are a region-appropriate and are a nice contrast to the other plants I have. I'll carry on with them and see if they bounce back. If not, I'll probably just try them again right away.

The tank:
I've added cariniana (sava) pods to the tanks. I don't know if the openings are large enough to hang eggs in, but even if not, it doesn't hurt to have them. The Asellus quite like them. They also really like the coarse sponge filter. and are crawling into the sponge. I hope these silly bugs can eventually get out!

I've also determined that adding alder cone extract buffers the water from my acid. I'd previously only added the extract consistently to my 20 long, where I generally tend to see the pH rise faster than in my other tanks. Since adding it to other tanks during water changes, I'm definitely seeing the alder cone extract coincide with higher pH in those tanks. It lowers the pH of RODI, but raises the pH of tank water + acid. It's surprising, but I'm not sure if it's actionable.

The tint: Looking nice and dark these days. 😍

IMG_2589.jpg
 

Wookii

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The tint: Looking nice and dark these days. 😍

It is looking good - I always find it difficult to maintain the tint longer term. How are you achieving it? Do you have something in the mesh bag on the right?

Also what is the floating plant on the top right?
 

brhau

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Thanks! The plant on the top right is Hydrocotyle leucocephala . It grows quite well. Some of the older, submersed leaves get yellow, and I trim those. But the ones near and above the surface look good. I don't think it grows in Asia, but I think I'll keep it nonetheless.

The mesh bag contains alder cones, and that's definitely what keeps the tint so dark. Every 1 or 2 weeks, I steep about a dozen alder cones in 1.5 liters of boiling hot water and add the extract to my water change. I found that the extract itself isn't enough to tint the water that dark (see the earlier picture in the first post). However, if I add the spent alder cones to the tank in the mesh bag, it continues to leach tannins for a while, tapering off over the course of a week. I could simply add the alder cones directly, and I might start do that eventually to save time. The reasons I do it this way now:
  • Sinks immediately.
  • Keeps a more even level of tannins on the day of the water change, but this is probably only a difference of 1-3 days.
  • If the cones have seeds, they'll be held in the mesh bag, and I'll throw them out every 1 - 2 weeks. Depending on when the cones were collected, they can release seeds. Those add bioload, so I pick them off the top of the water and the sides of the glass near the surface, where they stick. Depending on how thorough I want to be, that can get tedious, especially with 6 tanks.
  • I can move the bag to other tanks. Overall, I have more control of the tint and probably use fewer cones this way.
Cheers
 

brhau

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The 4 pairs of Parosphromenus phoenicurus arrived on Tuesday! Two of the males are large and were darkly colored even in their shipping bags. The shipping water had very high conductivity (~2500 us/cm) and was yellow-green, possibly from acriflavine or some other additive. After a lengthy acclimation, they've settled into the 10 gallon colony tank (picture at the bottom of the post).

The paros are REALLY shy. I didn't appreciate before how slow moving they are. They can be quick when startled or striking at an insect, but normally they look like they're in slow motion. I watched one try to chase a grindal worm falling to the floor, and it was traveling slower than the worm was. 😂 It's worth noting, though, that for slow-moving fish, they can jump. For the drip acclimation, I set up a water bath in a 5-gallon horizontal bucket and floated a plastic shoebox in it. Within the first hour, I saw that one of the fish was in the water bath outside of the shoebox. Not ideal. He had to clear about 4 inches to get out. I quickly netted him and returned him to the correct water, but was careful to cover with plastic wrap the rest of the way. I typically keep my tanks cracked open to allow more airflow for the floating plants, but not on this one. My understanding is that they don't often jump from aquariums (just temporary containers) but I'm not taking any chances.

The fish usually stay well hidden until feeding time, at which point I typically see 2 – 4 of the fish at a time. The most I've seen at one time is 7, the first time I offered grindal worms. I'm trying to offer those sparingly, but it's so far the only thing that gets their attention. Once I draw them out, I add BBS, which they started taking today.

I'll try to get some macro shots of the animals next week. Hopefully they'll be a bit more used to me by then.

Other foods:
I've started a Chlorella vulgaris culture, and it's been slow going. I bought it in petri dish format and started with a streak of it in about 150 ml of f/2. After several days, I expanded that out to 1L, and it's still fairly pale green. Hopefully it will saturate soon and I can start a moina hatch next week.

IMG_2671.jpg


Water parameters:
I decided to set a higher target range for my pH, between 5 and 5.5. I think it will be easier to keep stable this way, and it requires that I add quite a bit less acid. I made this change because I noticed that my inverts aren't doing great, and I lost of a few of the Boraras. I suspect that there was too big a pH differential between the tank water and the incoming water at water change time. Though the tank itself did not move more than 0.5 pH units, the incoming water can create local areas of very low pH water before the mixing occurs. Didn't want to risk this being an issue. Another benefit of not adding as much acid is that I can run a lower conductivity, which is now down to around 20 us/cm in the display tank.

Plants:
The only update here is that the Bucephelandra (not seen in this tank) seem to be doing fine. The biofilm mostly went away on its own, and I see some small new growth, though it's very slow. So that's encouraging.

More soon.

Here's the 10-gallon:

IMG_2674.jpg
 

brhau

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The male I shared above actually isn't the biggest/most colorful one, but he does seem to be in charge, patrolling the much of the open area on the right side of the tank. Hopefully I can get some pictures soon of the biggest guy, but he doesn't come out often. The fish overall seem more comfortable in the tank. For the first 4 days or so, I couldn't observe any of the males eating, and everyone stayed hidden most of the time. Starting from about Day 7, I can draw most of them out with BBS alone. I can still only see a max of 7 out of the 8 at any one time, so I make sure to squirt food into the planted areas. Interestingly, the two bigger males don't seem to take grindal worms. They chase and play with it, but strongly prefer BBS.

So far, most of the social behavior I've seen looks like territorial aggression, particularly obvious between the males (flaring, as seen above). I have seen some head-down posture in the females, with males approaching and then retreating to the caves (they use them all, including the sava pods). But no "sexy eyes" or courtship dress in the females that I've seen yet.

Foods:
The Chlorella vulgaris culture had stalled out, and I've since concluded that the f/2 medium isn't rich enough to support them in freshwater. I've grown it in that medium before, but I had the benefit of a warm room with 24 hours of light and a shaker. I should probably use the <Biobizz Fish Mix>, but being stubborn about what has worked for me in the past, I've ordered some Bold's Basal Medium to try first instead. In the meantime, I've supplemented the water with 2X the f/2 concentrate (so it's technically f/1) and also added some all-in-one fertilizer to increase the nitrogen content.
 
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brhau

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The fish:
I've seen all 8 fish come out at feeding time, which is comforting. One of them, however, isn't doing well. it's this male:
_DSC0467.jpg

I believe this is the one who jumped out of the acclimation container, so he went from bag water > tap > bag water, which is a lot of osmotic stress over a ~20-minute period of time. This is the one animal I haven't seen eat yet, and he hides a lot. Still, I see him come out at feeding time, which is encouraging. Will keep an eye on him.

The females occasionally show some coloration in the fins. I think it must be mood-dependent, since at times they appear completely clear:
_DSC0396.jpg


And here is one of my smaller males:
_DSC0460.jpg


Foods:
The paros continue to be unenthusiastic about grindal worms, which is definitely not the case with the Boraras and Betta I have in other tanks. It's unexpected, to say the least, to see any fish reject a worm of any kind! Consulting with other keepers, there are a couple possibilities:
  1. Kevin Marshall, the UK coordinator of The Parosphromenus Project (not sure if he's on here?) believes there is some species dependency on willingness to eat grindal worms. He's also had P. phoenicurus that has rejected them in the past.
  2. I might be overfeeding. Currently, I rinse the BBS in a square sieve. I can gather the BBS in the center to make about 1 square cm. I've been feeding this twice a day to 8 animals. That doesn't seem like a lot of food to me, but I was advised that half of this is sufficient. So I'll try that and see if the response to grindal worms changes at all. I can also try offering the grindals on the first day after the fast day.
Moina: On day 12, these finally started hatching! I'd almost given up on this batch. I think if I looked more carefully, I might have seen them sooner. They're harder to see than I expected. I have them in a small mason jar right now on the window sill with live Chlorella. There are maybe 15 - 20 of these in 400 ml of water. I'm not sure if this indicates an unhealthy culture, but I do tend to see the algae settle at the bottom of the jar, leaving the water somewhat clear. It still seems to grow, however, albeit a lot slower than I would have thought. So I just keep resuspending it when I can.

Inverts:
I think I need to give up on these. No sign of the Tangerine Tigers. The Asellus have drastically reduced in number. I no longer see any adults and just a few of the juveniles (I had over 50). I suspect that they succumbed to acid stress. Even though I keep the tank at a higher pH now, I doubt any inverts will appreciate the calcium-poor water over the long term.
 

Wookii

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Great pics again!

No sign of the Tangerine Tigers. The Asellus have drastically reduced in number. I no longer see any adults and just a few of the juveniles (I had over 50). I suspect that they succumbed to acid stress.

Are you still running on zero GH? If so, I suspect no inverts will survive that - I know @Conort2 has managed to successfully keep the Tangerines in low TDS water, but I believe he still maintains a GH of around 4 ish.
 

brhau

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Great pics again!
Thanks

Are you still running on zero GH? If so, I suspect no inverts will survive that - I know @Conort2 has managed to successfully keep the Tangerines in low TDS water, but I believe he still maintains a GH of around 4 ish.
I am, and I think you're right. There seem to be multiple schools of thought on where to keep the conductivity. Most of the literature from the Parosphromenus Project says to keep the EC as low a possible (below 30) which is effectively a GH of zero. There are some shrimps that live in the same habitats, such as Caridina s. simonii. I don't have a way to buy those, however. Also, the suggestion to use Asellus aquaticus came from those paros forums, so presumably those are also extreme blackwater tanks. Presumably these inverts get calcium and other minerals from their diet.

That said, there is a breeder of P. phoenicurus who keeps them at TDS 70 - 80 (EC 117) and also keeps them with CRS. He recommends keeping the conductivity extremely low if breeding paros is the #1 priority. That said, he was able to find TDS 70 - 80 as a sweet spot where the shrimp still survive and the paros still breed, but it's not optimal for either.

I have a betta tank that I keep at TDS 100. All GH, no KH. I'll measure the GH there to see what it works out to. I imagine it's 5 or 6. So maybe TDS 70 - 80 is more like GH 4.
 
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