Charlotte,

I've tried a number of techniques with small salmonids.  Here's a list.

1) freeze branding. quick to apply.  my marks last 6 weeks or more, though
likely shorter with warm water fish ( this might be your primary problem I'd
guess).  I use brands made of bent coat hangers and liquid nitrogen as a
coolant.  In terms of pain felt by the fish, well, I tried it on myself and
it wasn't excessive.  This is the method I currently prefer for short term
visual marking.

2) Small external tags on operculum.  These had a tendency to fall off and
cause tissue damage which may then be prone to infection.

3) VI tags - described in adds in ads the journal Fisheries. These use an
applicator to slide a thin tag under the skin.  I found them useful and
inobtrusive for the fish when used in the field for release and
recapture/identification of individuals.  Some problems with tag loss.
These tags would be difficult to id individuals without capturing them again
(i.e. difficult to identify individuals in an aquarium).

4) Tattoos - Panjet markers can be used to provide rapid marks (tattoos).
Individuals can be identified by marking fish in different locations.
Longevity is good from what I understand (cold water fish again), though
I've never used this technique.

5) Latex injection - subcutaneaous injection of latex.  Slightly invasive.
Provides id of individuals by latex color and location. Some concerns about
it being invasive and the health effects of latex (I haven't tried this on
fish or myself).

Hope these suggestions help.

Steve McAdam
[log in to unmask]

-----Original Message-----
From: R C Marelius [mailto:[log in to unmask]]
Sent: Tuesday, August 15, 2000 10:19 PM
To: [log in to unmask]
Subject: non-invasive marking of small fish


I want to mark young breeding pairs of cichlids (Heros appendiculatus, F1)
in a large tank with several others of their own kind and size.  I do not
have tagging equipment and would hesitate to use it on such a small fish
anyway (4 -5" SL).  Due to their aggressive nature, I cannot pull the pairs
from the group, as all their energy would be concentrated on each other
then, rather than dispersed harmlessly among the crowd.

It takes them a few spawnings before their pair bond is secure enough to
prevent them from damaging each other once they are removed to a tank of
their own, but once they have formed a pair at all, they don't do well when
it is broken.   I can isolate them to catch them and mark them (with any
luck) now that they're busy preparing a nest site, but I can't keep them
isolated.  And they look just like everybody else, of course, when they are
all darting away from a net and trying to look like gravel.

Is there a glue I could use to place a metal or plastic dot on their dorsal
or caudal fin, or perhaps a dab of paint that would dry instantly on the
moist surface of a fin?  Can something be placed on the body surface
itself, given their excellent slime coat and the small size of their scales
(1 to 1.5 mm exposed)?  Has anyone some suggestions.

Charlotte Marelius
Just a hobbyist

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