Hyposalinity for transport and quarantine

[Curtswearing]

Terry,

It was a pleasure meeting you and having our discussion about Hyposalinity. The levels you were discussing to help with Osmo-Regulation were shocking but after you described it, it made a lot more sense.

Here's some info from one of your articles.

Significant portions of post shipment losses are due to osmoregulatory dysfunction and stress-mediated diseases occurring within the first week after transport (Johnson & Metcalf, 1982. Carmicheal et. al, 1984). Stress in fish causes osmoregulatory dysfunction (Harrell & Moline, 1992. Weirich et. al, 1992). This can lead to mortalities (Tomasso et. al, 1980). Reducing the gradient (difference in salinity) between the internal fluids of fish and the surrounding ambient water alleviates water and ion disturbance ((Wedemeyer, 1996). Manipulating the salinity of the transport water upward for freshwater fish and conversely downward for saltwater fish is effective for controlling osmoregulatory disturbances and reducing losses (Carneiro &Urbinati, 2001). Fish held in water that is close to isotonic (the salinity of the surrounding ambient water is close to the internal fluids of the fish) have increased stress resistance (Lim et. al, 2000). These fish also display a significantly lower mortality rate at 7 days post shipment.

Just this month, there was another article in Advanced Aquarist that said...

The other advantage that is of great interest with hyposalinity, is the reduction of osmotic stress on fish with abrasions or lesions. In theory, the reduction of the osmolar gradient between the internal tissues and the surrounding environment would be beneficial to injured mucus and epidermal tissue. This reduction in the osmolar gradient, in theory, greatly reduces the loss of water from the fish to the surrounding environment. The ability to maintain hydration in an injured marine fish too small to administer fluids could prove very beneficial. Many more studies, which are ongoing at this time, and sample collections remain to prove this theorized aspect of low salinity.

That article advocating slowly dropping down to 11 PPT.

What PPT would you recommend for the average hobbiest assuming that they have a quarantine tank?

 

[NaH2O]

Just to clarify....is the hyposalinity for fish that have been shipped several days, or for fish that you are driving home from the LFS? What about fish ordered online?

 

[Terry B]

Hi Curtswearing,

It was great to meet you in person and get a chance to talk for a few minutes face to face. I had a good time meeting a lot of members at the meeting. My only complaint is that I spent 40 bucks on raffle tickets and didn't win anything.

New or radical ideas are always a bit of a shock and I usually experience resistance. I dealt with the same things years ago when I began promoting hyposalinity as a treatment for ich. Now this method is widespread and has been very successful. Unfortunately, those nasty ich buggers are beginning to adapt to a wider range of temperature and salinity. There are a couple of strains from Tawain that are resistant to hypo now.

I have been working to encourage some wholesalers, shippers, etc., to try shipping and holding reef fish in hyposaline conditions for some time. They haven't said that using a low salinity would not help. They just come up with excuses why it would be a pain or how others won't cooperate. Recently, the idea is beginning to get more serious consideration and it may be on the verge of getting funding for trials.

I have suggested a salinity of 14ppt. This allows for some margin of error between the required treatment level of 16ppt or less and the salinity of internal fluids of the fish. I figured that as long as the salinity of the water is slightly higher than the internal fluids of the fish then they would still be able to osmoregulate in a natural manner (albeit at a much reduced rate). We need more studies to determine the optimal salinity for our purposes. I think we need to look closer at how much it affects the pH during transport to.

As far as when to implement salinity manipulation I believe it can be used for trans-shipping, taking the fish home, for all holding facilities and for hobbyists during quarantine. Fish adjust quite readily to low salinity. They need more time to adapt back to a NSW level again.

Cheers,
Terry Bartelme

 

[NaH2O]

Thanks for the info. When implementing hyposalinity in a quarantine situation (new arrival), how quickly can the salinity be dropped or raised? The span of a week, longer? Also, do you wait for the entire QT period before raising salinity to meet that of the tank?