Fish Necropsy, Repost from IBC BetterBettas Yahoo Group

[LiquidBlue]

This topic of getting a fish necropsy (necropsy is the animal version of autopsy)came up on the IBC yahoo group and Stephen Jones provided a very good explanation. With his permission, I am reposting his response.

Hello All,

My wife is the veterinary pathology resident at the National Zoo
(Smithsonian Institution). When I saw this question, I thought
perhaps I would get the straight scoop on how to handle this situation
optimally. Her recommendations are, with some translations in ():

The best thing to do is incise the coelom (abdominal cavity to us
humans)to expose the internal organs and fix whole in formalin (your
local vet will usually order or supply you with some 30cc or 60cc 10%
neutral buffered formalin bottles. If you think you want to do this
sort of thing routinely, you can typically get a few to have around.
They have a limited shelf life (~12 -18 months), so don't go crazy and
stock up, lol).

If you have a dissecting scope, you can take a look grossly, but often
on something so small it is difficult to see much of anything. It is
always good to do a wet prep on the gills if possible (basically press
the gills against a microscope slide, and cover with a cover slip).

Fish autolyze so quickly, that if they can just throw it in formalin
and get histo, they will probably get more useful information. (When a
fish dies, it starts to auto-digest itself, which is the normal first
part of decomposition)

As for histology…if they can manage to get their hands on formalin,
then they can just send off to a veterinary lab for cutting in and
processing…also likely for a fee (check with your vet, as we all know,
most doc-in-a-box vets don't have much interest in, nor knowledge of
tropical fish.)

Freezing is typically bad news. The ice crystals wreck the tissues
and make them next to useless for necropsy.

If you know a fish is a gonner, and we all know that, even though we
will still hope to win the lotto... The humane thing to do is to
euthanize it in carbonated water (soda water from the grocery store
works fine, and is painless). There are some anesthetic agents you
can order that also work well, but the carbonated water works well in
a pinch. Once the animal is dead, press the gills on a slide, cover
with a cover slip, use a razor blade, x-acto knife, or best, a scapel
or some surgical scissors to incise the abdomen from vent to gills,
let any water in the abdomen drain out, and then place the fish into
the formalin. That whole proceedure should take less than 30 seconds,
not counting the minute or so it takes to euthanize.


As to where to have a necropsy done, any of the state diagnostic labs
(usually associated with a vet school) will do it for a small fee.

I had a beautiful 'red dragon' (I know you guys hate 'trade names',
but it just sounds so cool!) sire develop some really bizarre tumors a
year or so ago that I had formally necropsied by an academic team of
vet. pathologists. The tumors looked exactly like that freak-fish on
aquabid a few months ago (white, pearly looking things, I have
pictures if anyone is interested). The tumor was a carcinoma, likely
of Malphigian cell origin (Malphigian cells are the fundamental
component of fish epidermis, so this was a skin cancer).
Interestingly the fish also had a kidney nephroblastoma (primary
kidney cancer), which makes for 2 primary cancers in the same fish.
This is essentially unheard of in species that only live on average 1
year or less (sure our show bettas live longer because we don't eat
them, but in the wild, bettas are probably snacks before they reach 1
yr). This fish was 22 months old. There was also evidence of
Mycobacterium sp. (friggen fish tuberculosis... which resulted in a
full barrack breakdown and sterilization, x2, and that setup is still
fallow, and will likely be steriziled at least 1 more time, and also
probably infused with INH in the pumps for at least a month before it
is torn down again and repopulated. I *HATE* pathogenic
Mycobacterium!). The case may be published at some point in the
future, if it is, I will get a scan of the article. And yes, I had
the water tested for carcinogens and teratogens, all negative ;^)

Anyway, I hope the info above on how to properly prepare a fish for
formal necropsy proves useful to some of you guys!


So there you go! What a lucky guy to have the veterinary pathology resident at the National Zoo right in his own home. And lucky us that he posted the info. Interesting, huh?

Thanks Stephen Jones for allowing me to repost this!

[bettaloha]

Interesting and informative stuff! Thanks for sharing this with us LB! :D

[DownSouthBettas]

Glad you posted it, it was good he wrote that I have always wondered....

Everytime I have a fish emergency I have to call the Ichthyologist who works at Seaworld! Those calls are not cheap! :blink:

[LiquidBlue]

Wow, what does the fish doc at sea world think when you call about bettas?!

[DownSouthBettas]

The first call was awkward, he is now the proud owner of 6 show fish!!!!!!!! :lmao: :lmao: :lmao: :lmao:

I have called him about 13 times in the last 2 years............he laughs when they tell him
its me calling.............. :D