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Jools wrote: ↑07 Jun 2020, 08:36 Here's a picture of one I caught in the Caribbean Sea off the northern coast of Venezuela. At this age they can move between freshwater and marine. 1555_G.jpg



Jools

Viktor Jarikov wrote: ↑11 Jun 2020, 00:47 I'd probably do more searching and reading online on the topic of how young is too young to go into full marine because there is no telling when you'd be helped sufficiently here, could be today, or could be never. IDK who keeps brackish or marine tanks on here. I am a 100% freshie. I think most or almost all people here are too. Perhaps Jools knows and could tag someone(s).

The plan to slowly increase the SG with WCs 0.001 unit at a time sounds reasonable to me, again, on paper, not from experience or knowledge.

It will take 20 weeks or 4.5 months during which time hopefully your pretty little rockets will do some growing and will have put on perhaps a couple of inches.

Are the sharks still stressed by the increased salinity and have no or suppressed appetite? Are they still hiding? I think they shouldn't. They are not of the hiding type, unless perhaps the lighting is too bright and/or there is little cover nearby to dive under in case of danger, as they perceive it.

I am sincerely excited to see someone actually doing what these fish need for a change, that is, transferring them slowly into brackish and marine, and reporting it along the way. This is the first time in my experience, so in a way, you are a trailblazer to me

It'd be awfully nice and helpful if you too chose to keep all your posts on these fish and what you are doing in one thread for an easy and convenient reading and learning experience now and for posterity.

Fishmandavew wrote: ↑13 Jun 2020, 20:25 Columbia’s sharks are born in fresh water to my knowledge and return back to the sea as they grow. As such kept three in fresh until around five inches when I started increasing the salinity of their six foot tank. Finally over the course of 6 months reaching 1.025 by which time they were living with a porcupine puffer, baitfish and zebra moray and around a foot in length. Finally moved them on at 16” to an lfs for their huge display tank to highlight the size and requirements of this fish which is all too often sold as a freshwater community fish

daviem wrote: ↑20 Jun 2020, 05:26 Ok I increased the salinity of the aquarium from 1.005/1006 to 1.007 and this appeared small lumps across the fishes sides I have a picture I will attached then the columbian shark keeper I was talking to advised me it maybe parasites and more salt will kill the parasites so I increased the salinity to 1.008 but the fish went frantic trying everything to get out Of the aquarium as far as pushing on the edges at the bottom to swimming frantically across the top so I removed 25% water then added RO water directly to the aquarium this brought the salinity back down to 1.006 they are swimming calmly now but look exhausted. What’s going on, do they have parasites or as someone told me is it possible the salinity increase was too quick? and the salinity increase burned their skin? Or is it a parasite that either likes or doesn’t like the salt? What’s your views?

Lycosid wrote: ↑20 Jun 2020, 18:15

daviem wrote: ↑20 Jun 2020, 05:26 Ok I increased the salinity of the aquarium from 1.005/1006 to 1.007 and this appeared small lumps across the fishes sides I have a picture I will attached then the columbian shark keeper I was talking to advised me it maybe parasites and more salt will kill the parasites so I increased the salinity to 1.008 but the fish went frantic trying everything to get out Of the aquarium as far as pushing on the edges at the bottom to swimming frantically across the top so I removed 25% water then added RO water directly to the aquarium this brought the salinity back down to 1.006 they are swimming calmly now but look exhausted. What’s going on, do they have parasites or as someone told me is it possible the salinity increase was too quick? and the salinity increase burned their skin? Or is it a parasite that either likes or doesn’t like the salt? What’s your views?

The issue with salinity is that it changes the osmotic pressure on the fish. A fish's internal salinity is somewhere between freshwater and full saltwater, and so a fish in freshwater has water "pushed" into its body by osmosis and a fish in full saltwater has water "pulled" out of its body by osmosis. A fish then needs physiological mechanisms to counteract this. In the case of a fish that changes between fresh and saltwater over time (ontogenetic change) these mechanisms also shift as the fish grows. This is why a Columbian shark will die as an adult if it is placed in freshwater - it's lost those mechanisms and developed other ones.

My guess is that Columbian sharks probably also take some environmental cues - if the water they are in is saltier they probably speed up developing those saltwater-tolerant mechanisms. But I can't find any studies on this, so I'm just taking an educated guess.

I would suspect that what's happening to your fish is that when the salinity changes on them it feels really strange to them until they adjust. The question is how fast they would adjust. One thing you could do is bring the salinity up slower. If you measured the amount of salt you need to add to the water to bring the salinity up to your target you could add the salt to the water in small batches over several days (testing the salinity, of course, in case your calculation was off) and let the salt slowly dissolve into the water. I once had a research student pour a bunch of salt into a tank (with no residents) rather than stir the salt into water first, and the salt took almost 24 hours to all dissolve (it was also ALL the salt needed to go from full fresh to full salt).

However, given the lack of data on this species, your best bet is to just pay attention to the fish and make sure they seem comfortable with their salt level.

daviem wrote: ↑05 Jul 2020, 18:01Someone said on another forum that they acclimated their fish straight from freshwater to marine the fish were fine in a reef tank for a short while then died, so no I’m stuck, did the salinity kill them or the reef environment.

daviem wrote: ↑05 Jul 2020, 18:01 Someone said on another forum that they acclimated their fish straight from freshwater to marine the fish were fine in a reef tank for a short while then died, so no I’m stuck, did the salinity kill them or the reef environment.

I added yet more live bacteria yet my aquarium won’t cycle. Won’t even start still no nitrites or nitrates but rising ammonia.