162 
Preserving 
In preserving specimens, those from a single collection (one place at 
one time seine-haul or net set) are usually preserved and shipped together 
to the museum. Sorting to species is done later at the museum. 
In preserving specimens the following points should be observed. 
Specimens should not be bent or crowded. While preserving, not more than 
half the container should be filled with fish. An effort should be made 
to have the fins extended and the mouth and gill covers in their normal 
position. A slit made into the right side of the body cavity will ensure pre- 
servation of internal organs (see Figure 48). Avoid cutting internal organs. 
Very large specimens may require injections of preservative into the muscles 
of the back; or better, slits into the back muscles from inside the body cavity. 
Delicate larval or oceanic fishes, or those with deciduous scales may be 
lightly wrapped in gauze or kept separately in vials. Larval and small oceanic 
fishes may be preserved in more dilute formalin — 5 per cent. Fishes with 
large spines or rough scales should be separated from the rest of the collection. 
Under certain conditions the strength of the preservative must be 
increased, e.g., tropical climate; specimens beginning to decay; very large 
specimens; and containers completely filled with fish (instead of half-filled). 
With a bit of extra care in handling, very fine specimens may be obtained. 
These will be easy to identify, easy to obtain data from, and may last over a 
century. It is therefore well worthwhile. If specimens are laid out flat in 
a pan, mucous, blood, sand, and vegetation may be brushed off. The 
specimens may be laid straight and the fins spread, and then covered with 
formalin. While fixing them in the pan, colour notes may be made. When 
the specimens are firm, they may then be carefully placed in jars filled with 
fresh preservative. 
Filling containers to the top lessens slop of fluid and wear and tear on 
the specimens during transport. It also adds extra protection against 
evaporation. 
Formalin 
The normal procedure in formalin preservation is to carry to the col- 
lecting site a number of bottles or cans suitable in size, partly full of con- 
centrated formalin. The live fish are dropped into the concentrated 
formalin. This kills them quickly and causes the fins to spread. The 
freshwater or seawater is added till the bottle is full (then the label). 
Ethyl alcohol 
When preserving with ethyl alcohol the following steps are taken: 
Fish are put (a) in 50% alcohol for a few hours to 2 days (the shorter period 
in high temperatures) ; 
(b) then in 60-70% alcohol for 7 to 14 days depending on 
specimen size. (Alcohol should be tested at least every 
other day and fluid changed or brought up to strength) ; 
(c) then in 70-75% alcohol for final storage. (These steps 
on preserving in alcohol from the British Museum In- 
structions for Collectors.) 
Ethyl alcohol can be reused if filtered and brought up to strength, or if 
redistilled. 
