[Coral-List] Potential effects from using MS.222 (tricaine methanesulfonate) on coral reefs (Taratau Kirata)

Rob Hilliard, imco rhilliard at imco.com.au
Tue Dec 2 22:14:36 EST 2008

Hi Taratau

I would be surprised if expensive MS.222 (Sandoz) would be a popular 
choice for using in open reef waters by the live reef fish food trade to 
catch large wrasse and groupers - either for slowing them down (it's not 
quick acting on large fish) or for keeping them under sedation/ narcotic 
state for long periods (it precipitates out and decomposes into 
non-effective and more toxic compounds relatively quickly - especially 
in light).  

The speed and level of anaesthesia achieved by MS.222 varies 
considerably (3 to +30 minutes) with water temperature, salinity, DO2 
and, most importantly, with fish size/biomass and particular species.   
If MS.222 were to be used heavily and irresponsibly on a patch reef 
during, say, the low water slack, you can predict the most potentially 
immediate side-effect will be substantial mortality losses to the 
damsels, humbugs, gobies, etc, because it is the smallest fish that are 
almost always the most sensitive.    Note the point made below that 
MS.222 in seawater becomes toxic when exposed to sunlight.     Very high 
doses (20% concentrations) of MS.222 are reported to be required to 
achieve narcosis in invertebrates such as annelid worms.

Our fish lab stopped using MS.222 as a fish anesthetic back in 1979 - it 
was quite expensive and a reported carcinogen - although there are some 
contrary claims, e.g 
We switched to the much cheaper benzocaine (which needs to be 
pre-dissolved in a little ethyl alcohol before using).   MS.222 breaks 
down quicker and into potentially more toxic compounds than benzocaine 
(which is a common topical pain killer, e.g. powerful throat 
lozenges).    You may be interested in the following snippets I trawled 
from Googling "MS 222"
editon by Hoar & Hickman.
"There is a very wide latitude in the permissible dosage,  and 
recommended amounts vary from 1:5,000 to 1:20,000. In practice, a 
solution of about 1:10,000 is usually found satisfactory; animals are 
placed in the solution until the desired level of narcosis is attained 
and then removed to their natural water for injection or operation.   
The sustaining dose for prolonged anesthesia (added to the water flowing 
over the gills) should be much more dilute (1:45,000). Solutions of 
MS-222 gradually lose their activity but a 10% solution will remain 
fully active if stored in a brown bottle for up to three days.  
Solutions in seawater will become toxic if exposed to light."

Ohr, E.A. 1976. Tricaine methanesulfonate--I. pH and its effects on 
anesthetic potency.  Comp. Biochem. Physiol. 54C:13-17.
In a nutshell:   Start with 0.01% in distilled water (pH will be about 
3.7 but if using in seawater there's no need to titrate this back to pH 
7-8 with NaOH).   A working stock solution is not possible - both MS.222 
and benzocaine tend to precipitate out.  Induction times take around 5 
minutes for 2-5 g fish. Recovery is about 4 minutes after returning to 
clean water.

Cheers and hope this helps,

Robert Hilliard
InterMarine Consulting Pty Ltd
Western Australia
Mob:   +61 427 855 485
Office: +61 8 6394 0606;   
Fax:    +61 8 9255 4668
*rhilliard at imco.com.au*
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