Speaking of TSN runts, dinks, and Co...
- Thread starter thebiggerthebetter
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wednesday13
Hi Russ, do you know or have you heard anything about corruscans temp requirements? It has been suggested that perhaps our corruscans hasn't fed for 5-6 months now due to warmer water (see below). I wanted to ask Darren Palfrey aka Dazzapolypterusweeksii but he is not on the MFK anymore. He has had a corruscans for many years.
Exchange with KLT on YT:
KuhliLoachTrainer This reminds me of what happened with Twig the firewood catfish's fast from November to January, except I am not nearly as optimistic. Do you think temperature might have to do with it? I am thinking back to our June 21 2024 discussions about temperature, maybe the tropical climate of Naples is proving to be a long term detriment to Widmer just like it was to the white sturgeon…. Other than that, I don't really know what to say, this is a risky and undesirable situation. At least Widmer isn't visibly dying!
Fish-Story.. I think the corruscans natural range is wide enough to include tropics or at least subtropics, no? I'd have to look up their temp requirements. Off the top of my head, I doubt temp, although it'd be a good explanation. Well, Widmer has been now in the 80F water versus 86F. So far no natural appetite comeback. No, he is not sick visibly at all. Just an absolute zero appetite. I am hoping simply internal parasites. If he doesn't start to feed so I could give him meds through feed, I'll have to inject or forcefeed. Baths are not as efficient, especially for the poorly water-soluble praziquantel.
KuhliLoachTrainer As far as temperature requirements and range go, Wikipedia says the natural range of this species of surubi is the Sao Francisco and Parana-Paraguay rivers. Assuming climate data from cities can be used to get an idea of water temperature across the year, only the cities near the headwaters - the northernmost and warmest parts - of those rivers are on par with Naples…………… Corumba (near the headwaters of the Paraguay River), Uberlandia (near the headwaters of the Sao Francisco River) and Santa Fe do Sul (near the headwaters of the Parana River) are all tropical climates like Naples, and they have annual average temperatures in the 22-26C range which overlaps Naples' 24C annual average, so if Widmer came from the parts of the rivers around those cities, I would assume he would be fine temperature wise in Naples…………… But given that far more of the range of those rivers is further to the south, which consists of subtropical climates with considerably colder annual means than Naples, it's more likely that he comes from one of those parts. For instance, Corrientes which is close to the halfway point between the Parana's headwaters and its mouth has an annual mean 3C colder than Naples, and Buenos Aires which is near the Parana's mouth has an annual mean 3C colder than Naples. For a close-to-home-analogy, this the equivalent of the differences in the annual means between Naples and Gainesville in North Central Florida (3C) colder and Wilmington in Southeastern North Carolina (6C colder)………….. Also note that subtropical and tropical are not equivalent terms: just because the range of a fish goes into the subtropics doesn't mean it can handle the tropics. Subtropical fish have been known to tolerate year round heat very badly as
duanes
has learned by way of keeping Gymnogeophagus species from similar South American locations to P. corruscans at tropical temperatures and having them fungus up and die. You can ask them about this if you'd like more information. Hope this helps…………………. I did see that suggestion from Hukit and yes, I too think that doing what they did will be appreciably more effective than a bath. Because of the huge mouth of surubi it will surely be easier than with a smaller mouthed fish to force feed medicine or medicated food
Fish-Story Thank you so much for this homework! It surely strengthens your case for the temperature factor………………… One thing that can be added is that the air and water temps may or may not be in direct correlation. The mid and bottom waters of glacier fed rivers, like the Amazon, remain cold for great distances of hundreds of miles, if not a 1000 miles in the Amazon case. IDK if the rivers you mention are glacier or melting snow fed……………. I assumed the main difference between a fish from subtropics vs tropics was that they could handle cold snaps and the cooling of the water to 50-60F, which could not be said of the tropical fish. IDK if the subtropical fish need the cool off to remain in good health and condition. I'd assume they do not. IDK also if generalization is fair here. It may or may not be………………………………. "Also note that subtropical and tropical are not equivalent terms: just because the range of a fish goes into the subtropics doesn't mean it can handle the tropics. Subtropical fish have been known to tolerate year round heat very badly as Duanes has learned by way of keeping Gymnogeophagus species from similar South American locations to P. corruscans at tropical temperatures and having them fungus up and die. You can ask them about this if you'd like more information. Hope this helps."……………….. ***Yes, it's a great piece of intel!!! It argues against my thoughts on a factual basis, although it is a single fact. Still this is very valuable……………………….. All in all, I'd say that you are very well may be unto something here! Because Widmer showed no big problems like this with the feeding before. Why the sudden and long fast? And you point out it is coinciding with the warmest water temp. Maybe you've cracked it for me/us all!.................................... I am happy Widmer is now (accidentally) in the 6F-7F cooler water at 80F. Maybe I should leave him alone until the water begins to cool down in October and see if he begins feeding on his own and proves your hypothesis. I could even place him in the 25K because it is the same cooler temp but don't want to yank him around like that too often, given what can happen to big fish simply moving tanks.
Fish-Story One thing that doesn't quite align with the temperature hypothesis is that Widmer was moved to the 4500g in the beginning of March and still had couple cooler months to adjust and start feeding, which he didn't do. This could be have been due to his general finicky nature though, which was then in a cou0ple of months exacerbated by the temp per your explanation.………………………. I need to consult with other corruscans owners on what temperature dependence they have seen if any.
1. From Planet Catfish and FishBase corruscans appears to have a slighly lower temp range of 72-79F.
2. AI: The native temperature range for the Pseudoplatystoma corruscans, also known as the spotted sorubim, is 22.0–26.0°C (71.6–78.8°F). The spotted sorubim is native to river basins in South America, including the São Francisco and Paraná-Paraguay rivers. It is a migratory catfish found in fast-flowing rivers as well as floodplains. The fish prefer soft, slightly acidic, or neutral water conditions.
3. Practical FishKeeping: average temp 25C.
4. Josh of the OFR: corruscans are finicky in their experience. The usual hunger strike is 3 months. Josh recommends forcefeeding our fish since it hasn't fed in 6 months. He thinks corruscans temp requirements are no different from other TSN and Amazonian fish in general.
5. From this well known chart, the native range is definitely cooler than Amazon on average but about half of the range doesn't look too different:
2. AI: The native temperature range for the Pseudoplatystoma corruscans, also known as the spotted sorubim, is 22.0–26.0°C (71.6–78.8°F). The spotted sorubim is native to river basins in South America, including the São Francisco and Paraná-Paraguay rivers. It is a migratory catfish found in fast-flowing rivers as well as floodplains. The fish prefer soft, slightly acidic, or neutral water conditions.
3. Practical FishKeeping: average temp 25C.
4. Josh of the OFR: corruscans are finicky in their experience. The usual hunger strike is 3 months. Josh recommends forcefeeding our fish since it hasn't fed in 6 months. He thinks corruscans temp requirements are no different from other TSN and Amazonian fish in general.
5. From this well known chart, the native range is definitely cooler than Amazon on average but about half of the range doesn't look too different:
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KuhliLoachTrainer Yes, I know about glacier and snowmelt fed rivers being much colder than the air temperature: in fact I think it's a really fascinating topic so thanks for bringing it up One such example is the Solimoes: even as far from its source as Manaus at the Meeting of the Waters the Andes glaciers/snowmelt are powerful enough chillers to keep it at 22C which is 5C colder than the annual mean of Manaus…………….. Another noteworthy demonstration of glacier/snowmelt chilling effect is the Rio Magdalena: the impression Duanes got when they swam in the mouth of the river (the northernmost, warmest part draining into the tropical Caribbean) is that the water was about 21C, which is 7C colder than the annual mean of Barranquilla at the river mouth. If it's that cold at its mouth, my guess is that closer to its source, at say Barracabermeja, it would be in the teens C……………………….. I don't think any of the 3 rivers we were talking about are glacier fed, though: none of the information I could find suggested such. But if they were, that would of course strengthen the diagnosis even more……………………………….. As far as generalizations go, I think studies need to be done on this, but I think many subtropical fish needing the cool off isn't unreasonable to assume if Duanes' experience is to go by, they have repeatedly and explicitly stated that's what their Gymnogeophagus have done better with. Another thing to consider is what they said about them fungusing up if kept too warm for too long: they have mentioned that bacteria and fungi do better at higher temperatures and this may be directly correlated with the fungusing up of the Gymnogeophagus that don't get a cooldown. Not only would stress from too warm water weaken their immunity, but fungi and bacteria do better in warmer temperatures from what they have tested as a microbiologist, so the infections are especially bad with no cool down………………………… The rest of your comment sounds like a plan. Only thing I'd add is, maybe try a chiller to get the water down to 19-23C or so and see what happens? 27C still might be a bit high at this point.
Fish Story: “One thing that doesn't quite align with the temperature hypothesis is that Widmer was moved to the 4500g in the beginning of March and still had couple cooler months to adjust and start feeding, which he didn't do.”
KuhliLoachTrainer I think it actually does, because the cooler months were not really cooldowns at all compared to their Argentinian equivalents. January this year in Naples was colder than average but was 2C warmer than July in Corrientes and 5C warmer than July in Buenos Aires, while February and March were around 21-22C and so also considerably warmer than their equivalent August/June in Buenos Aires or March/November in Corrientes. Then April and May this year were similar to the warmest months in Buenos Aires and Corrientes, which is to say nothing of the even warmer June, July, and August. So even in the cooler months the water was still considerably warmer than it would have been in the coolest parts of the year in the Argentinian cities, together with the faster warmup.
One such example is the Solimoes: even as far from its source as Manaus at the Meeting of the Waters the Andes glaciers/snowmelt are powerful enough chillers to keep it at 22C which is 5C colder than the annual mean of Manaus…………….. Another noteworthy demonstration of glacier/snowmelt chilling effect is the Rio Magdalena: the impression Duanes got when they swam in the mouth of the river (the northernmost, warmest part draining into the tropical Caribbean) is that the water was about 21C, which is 7C colder than the annual mean of Barranquilla at the river mouth. If it's that cold at its mouth, my guess is that closer to its source, at say Barracabermeja, it would be in the teens C……………………….. I don't think any of the 3 rivers we were talking about are glacier fed, though: none of the information I could find suggested such. But if they were, that would of course strengthen the diagnosis even more……………………………….. As far as generalizations go, I think studies need to be done on this, but I think many subtropical fish needing the cool off isn't unreasonable to assume if Duanes' experience is to go by, they have repeatedly and explicitly stated that's what their Gymnogeophagus have done better with. Another thing to consider is what they said about them fungusing up if kept too warm for too long: they have mentioned that bacteria and fungi do better at higher temperatures and this may be directly correlated with the fungusing up of the Gymnogeophagus that don't get a cooldown. Not only would stress from too warm water weaken their immunity, but fungi and bacteria do better in warmer temperatures from what they have tested as a microbiologist, so the infections are especially bad with no cool down………………………… The rest of your comment sounds like a plan. Only thing I'd add is, maybe try a chiller to get the water down to 19-23C or so and see what happens? 27C still might be a bit high at this point.Fish Story: “One thing that doesn't quite align with the temperature hypothesis is that Widmer was moved to the 4500g in the beginning of March and still had couple cooler months to adjust and start feeding, which he didn't do.”
KuhliLoachTrainer I think it actually does, because the cooler months were not really cooldowns at all compared to their Argentinian equivalents. January this year in Naples was colder than average but was 2C warmer than July in Corrientes and 5C warmer than July in Buenos Aires, while February and March were around 21-22C and so also considerably warmer than their equivalent August/June in Buenos Aires or March/November in Corrientes. Then April and May this year were similar to the warmest months in Buenos Aires and Corrientes, which is to say nothing of the even warmer June, July, and August. So even in the cooler months the water was still considerably warmer than it would have been in the coolest parts of the year in the Argentinian cities, together with the faster warmup.
thebiggerthebetter
These guys are from Argentina as KuhiliLoachTrainer also mentions. A comparable fish for the location would b Caribe piranha and also dorado which are also known to “withstand” cooler average temps. Ur dorado do just fine in ur location. I still wouldnt b certain this guy is actually wild caught tho so its 50/50 for the cool temperature debate. “Pintado” aka p. Corruscans is the most commonly aquacultured species of TSN… right up there with p. Fasciatum for their fast growth and quick yield for meat. Theres quite a few keepers who have large size albino/leucistic corruscans in “community” style tanks with stingrays in brazil so id say an average “tropical” temp is fine for them.
IME catfish become spoiled and quite often refuse food for months when u mess with their regular schedule. Ive had RTC hunger strike for 2-3 months when moved across the room just the same.
Ive been following ur vids closely and have been hoping this guy came around and started eating again. IME its best to just leave them be and stop messing with them. Every time u move them or mess with their regular schedule ur just re starting the clock for them being annoyed/scared/bothered and not feeling comfortable enough to eat.
Many moons ago we had this same debate about ur wels catfish. We were worried ur florida temps were too hot for him. Thats on a much steeper curve also. Winter temps of freezing compared to maybe 68 degree winters for argentina.
Eventually ur glanis “acclimated” just fine. Even being in florida ur still having seasons of temp fluctuations just like u would anywhere else. Were right on the cusp of “fall” so id wager ur guy starts feeding again soon here with the coming temp drop. I wouldnt pull him out for injections or move him again until spring. As always, stress is worse than anything else, even high temps. If i can remember correctly this guy has given u hunger strikes before like when u got him and again when u moved it into the 1800. Just gotta ride it out and b patient which i know very well isnt easy with fish u care for and like alot… we often break before the fish do. Keep offering food. Removing uneaten and repeat… he will break eventually.
fingers crossed for u my friend.
Many thanks, Russ! You recall correctly that we had a hard time getting Widmer to start feeding well when he came. Took about a month. I have just re-watched our videos of when he was moved to the 1800g and I didn't mention any significant trouble, so he must have started feeding within a reasonable period of maybe a week or 2. Those were more reasonable delays.
The delay in the 4500 gal had been Mar 12 2025 to Aug 12 2025. That was 5 months of not witnessing even a try but only a total disregard for feed when everyone else around him fed well. It didn't look like he was bothered by tank mates to any significant degree to explain the total lack of appetite.
Would you personally still have kept him in the 4500g and kept hoping?
Widmer's been in isolation in 300g Aug12 to today's Aug 26, so 2 weeks. I offered the usual VitaChem'ed herring 2x. Zero interest. Like you said I should probably try daily. Also try mullet he last ate so well in the 1800g. Maybe try garlic juice too. Earthworms? To today, he has not eaten in 5.5 months. Lost half body weight. Was robust. Now slim.
Or move him into the 25K for the highest risk and highest reward?
Do you think such a delay may point to internal parasites, warranting medicating?
***
Josh of the OFR advised to force-feed Widmer because the delay is so long.
***
I must admit your perspective to let them be is a bit new to me. I'd probably reply that it is good to know with which ones to wait and with which ones to act, both in general, species-wise, and with individual fish (like your RTC that sulked for 2-3 months; this is not normal for an average RTC).
The delay in the 4500 gal had been Mar 12 2025 to Aug 12 2025. That was 5 months of not witnessing even a try but only a total disregard for feed when everyone else around him fed well. It didn't look like he was bothered by tank mates to any significant degree to explain the total lack of appetite.
Would you personally still have kept him in the 4500g and kept hoping?
Widmer's been in isolation in 300g Aug12 to today's Aug 26, so 2 weeks. I offered the usual VitaChem'ed herring 2x. Zero interest. Like you said I should probably try daily. Also try mullet he last ate so well in the 1800g. Maybe try garlic juice too. Earthworms? To today, he has not eaten in 5.5 months. Lost half body weight. Was robust. Now slim.
Or move him into the 25K for the highest risk and highest reward?
Do you think such a delay may point to internal parasites, warranting medicating?
***
Josh of the OFR advised to force-feed Widmer because the delay is so long.
***
I must admit your perspective to let them be is a bit new to me. I'd probably reply that it is good to know with which ones to wait and with which ones to act, both in general, species-wise, and with individual fish (like your RTC that sulked for 2-3 months; this is not normal for an average RTC).
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KuhliLoachTrainer:
Thanks for linking that 2020 surubi study, I really enjoy reading it in general so a nice surprise to seePersonally, I take recommended temperature ranges from online sources with more than a grain of salt because a lot of the time they can be shockingly far off. I'll give you some examples:
-Turquoise/umbee cichlid. These are often imported from the Magdalena: refer back to what I wrote about how chilled the waters of the Magdalena are. I have seen numerous sick umbee cichlid threads on Monster Fish Keepers where the fish were being kept at temperatures in the high 20sC (which a bunch of online sources recommend), for which Duanes recommended lowering the temperature on the basis of the colder Magdalena waters.
-Central American cichlids in general. You can find a thread about this by Stanzzz7 on Monster Fish Keepers titled ‘Are we keeping our cichlids too warm!’
-Some Rift Lake African cichlids. I don’t remember many specifics here but I do remember Millingu reporting theirs doing well at temperatures around 22C, around 2-6C colder than several online sources recommend. If you ask them I am sure they’d be happy to elaborate.
-Black, striped, and neon kuhli loaches plus Burmese loaches. All of these species are recommended to be kept in the mid 20sC to 30C by various online sources, but I have kept mine at 19C for months if not years with no issue whatsoever.
-Cardinal tetras. I can’t find this study no matter how hard I look, but I’ve seen one that showed cardinal tetras have notable (as in >3%) mortality over time at >28C compared to 25-27C having no mortalities, but a lot of online sources recommend >28C temperatures for them.
-And then there’s also a perhaps unexpected source, River Monsters. If you watch the episode River of Blood, Jeremy’s fishing in the winter where the air temperature is considerably colder than 22C, the water temperature is stated to be cold enough that most dorado aren’t feeding, he's wearing a jacket, and despite all this he catches a big surubi that did not stop feeding. That would rather contradict the lower ends of the recommendations you listed.
Hope this helps
Fish Story:
Thank you so greatly! For the last point, as being relatable to our corruscans case, yes, you are probably correct but our concern is the high end of the range and a potential need for a cool off or not. Was the River of Blood the San Francisco river?
Thanks for linking that 2020 surubi study, I really enjoy reading it in general so a nice surprise to see
Personally, I take recommended temperature ranges from online sources with more than a grain of salt because a lot of the time they can be shockingly far off. I'll give you some examples:-Turquoise/umbee cichlid. These are often imported from the Magdalena: refer back to what I wrote about how chilled the waters of the Magdalena are. I have seen numerous sick umbee cichlid threads on Monster Fish Keepers where the fish were being kept at temperatures in the high 20sC (which a bunch of online sources recommend), for which Duanes recommended lowering the temperature on the basis of the colder Magdalena waters.
-Central American cichlids in general. You can find a thread about this by Stanzzz7 on Monster Fish Keepers titled ‘Are we keeping our cichlids too warm!’
-Some Rift Lake African cichlids. I don’t remember many specifics here but I do remember Millingu reporting theirs doing well at temperatures around 22C, around 2-6C colder than several online sources recommend. If you ask them I am sure they’d be happy to elaborate.
-Black, striped, and neon kuhli loaches plus Burmese loaches. All of these species are recommended to be kept in the mid 20sC to 30C by various online sources, but I have kept mine at 19C for months if not years with no issue whatsoever.
-Cardinal tetras. I can’t find this study no matter how hard I look, but I’ve seen one that showed cardinal tetras have notable (as in >3%) mortality over time at >28C compared to 25-27C having no mortalities, but a lot of online sources recommend >28C temperatures for them.
-And then there’s also a perhaps unexpected source, River Monsters. If you watch the episode River of Blood, Jeremy’s fishing in the winter where the air temperature is considerably colder than 22C, the water temperature is stated to be cold enough that most dorado aren’t feeding, he's wearing a jacket, and despite all this he catches a big surubi that did not stop feeding. That would rather contradict the lower ends of the recommendations you listed.
Hope this helps
Fish Story:
Thank you so greatly! For the last point, as being relatable to our corruscans case, yes, you are probably correct but our concern is the high end of the range and a potential need for a cool off or not. Was the River of Blood the San Francisco river?
5+ months is more than a long time i agree. I’d leave him in the 300 for now so its easier to work with and theres no outside stress from other large tank mates. Praziquantel never hurts for treatment IMO… if u do choose to force feed id include prazi in the mix. It works very well and quick when ingested for any kind of parasites.
The debate is always a tough one to take physical action or stay with a hand off approach. Rich/Josh have force fed fish for years as “last case scenario”… its 50/50. Some fish bounce right back after and others dont.
If it is infact the high temps affecting him. From an avid fishermen standpoint. Nothing will kill a fish quicker than high temps and high stress combined. They pretty much go belly up immediately. Thats my fear for taking him out to hand feed or inject or even just move it again right now.
Whats the temp difference between ur 300 and the 25k? Im assuming the 25k has the coolest water. Im sure u could run a pump from the 25k to the 300 to cool widmer off a bit.
Im sorry i cant offer more help my friend. I hope it cools down in the next few weeks and this guy decides to eat again for you.
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Good I read your reply in the nick of time. I was just about to catch him in a clear plastic bag and place him in his "forever" tank, the 25K. It's heart wrenching seeing him sitting in one end of the too-small for him 300g.
My first choice of internal antiparasitic treatment is always prazi+metro, both compatible and very mild.
But before that I will try to entice him to feed by himself with other feeds and/or garlic.
From everything I've learned after we began debating the temp factor, I think the temp factor is highly unlikely. I am not worried about the temp anymore. I will work with the parasite guess, having zero other guesses.
The 300 is fed by overflow from the fan-cooled 25K, so both are at 80F.
My first choice of internal antiparasitic treatment is always prazi+metro, both compatible and very mild.
But before that I will try to entice him to feed by himself with other feeds and/or garlic.
From everything I've learned after we began debating the temp factor, I think the temp factor is highly unlikely. I am not worried about the temp anymore. I will work with the parasite guess, having zero other guesses.
The 300 is fed by overflow from the fan-cooled 25K, so both are at 80F.
Id stay in the 300 for the sole purpose of meds. Much cheaper and achievable to treat over the 25k lol… for a fish thats not eating anyway. Hopefully the meds nip whatever this is in the butt. Is there any way to slow the flow on the 300 to treat the water? I still use meds pretty effectively with autodrips going. I know ur tanks at the “end of the line” are dumping pretty quick tho. Only other thing i can think of is trying feeding tongs to try and get em to hit something out of interest or even anger just to get a meal.
