1. Overview of Otolith Thin Slice Method
SDAFS Catfish Technical Committee
2014 Catfish Aging Workshop

2. Procedures Remove and dry Set in epoxy resin
Thin slice using a slow speed precision saw
Mount thin slice to a slide using Cytoseal™
View – using a fiber optic light and dissecting scope

3. List of Items Used For Thin Slice Method
Slow speed precision saw (Isomet 1000) and cutting fluid (Isocut Plus Cutting Fluid)
Epoxy resin and hardener (West Systems 105 epoxy resin and 207 hardener)
Ice cube trays
Disposable plastic cup and spoon
Microscope slides
Cytoseal™ 60
Forceps
Warm water
Paper towels

4. 2. Set otolith in epoxy resin
-Mix resin and hardener in a disposable cup
-Pour base layer of epoxy and let harden (~4 hours)
-Set otoliths in the tray
-Cover with a second layer of epoxy resin and let
harden (~typically overnight)

5. 2. Set otolith in epoxy resin
Set otoliths in resin with posterior edge near the edge of the epoxy resin
Be Consistent! Set all otoliths with
the same orientation to be able to
make the same, consistent, cut on
each otolith.

6. 3. Thin slice w/slow speed precision saw

7. 3. Thin slice w/slow speed precision saw
Align the saw blade
slightly to the right
of the core of the otolith
Zero the micrometer, set
speed to 200 , lift chuck
counter balance and push
the blade button

8. 3. Thin slice w/slow speed precision saw
Raise the counter balance, spin the
micrometer wheel until .025” appears
on the digital readout
Cut off the posterior end of
the otolith

9. 3. Thin slice w/slow speed precision saw

10. 3. Thin slice w/slow speed precision saw
Rinse thin
slice in
warm water
and dry
Repeat process to
take a second cut

11. 4. Mount thin slice to a slide using Cytoseal™
Apply a drop of
Cytoseal™ to the
slide, place thin
slice on slide and
cover with
Cytoseal™
Remove air
bubbles
Allow to dry ~ 1 hour to view
both sides of thin slice

12. 5. View

13. 5. View

14. 5. View

15. 5. View

16. Same technique can be used for many species
Flathead catfish
Black crappie
Striped bass
Largemouth bass
Grass Carp??

17. Questions