Fish Behavior After Heron Attack

We have a 500 gallon pond with an assortment of Butterfly Koi,
Shibunkin, Cat Fish, and Gold Fish--all have names. We did not know
until 2 weeks ago that there are herons in Southern California. We
came home from vacation to find Groucho gone; while we did not see the
attack, there were gill remnants beside the pond, and the next day a
large heron was spotted in our yard. Our neighbors then excitedly
reported that they had seen 2 herons in their yard the previous day;
their joy at the sighting was substantially greater than was ours. The
circumstantial evidence is pretty strong that Groucho lost the heron
vs. fish battle. Anyway, 2 scarecrows and an electric fence seem to
have protected us since then.

The problem now, though, is that our fish have been seriously
spooked. Or at least that is what we surmise. Prior to our vacation,
they were quite active and seemingly fearless. Afternoon is feeding
time, and we could anticipate the fish once they saw us to start
circling furiously in anticipation of their food. Now, they are
profoundly less active, and head for the bottom when they see us. If
we sneak up on them at night, and suddenly turn on the flashlight, we
discover that they are more active than during the day, but then
immediately they hunker down on the bottom until we leave.

In hopes that the problem was something other than psychological,
I tested the water for pH, ammonia, and nitrates--high pH (normal for
us), but all other parameters normal. I exchanged about 20% of the
water (using a dechlorinator) to no avail. We have tried withholding
food in hopes of enticing them to the surface, but their food reserves
and the algae in the pond keep them on the bottom. We have tried
feeding them while standing quietly at the pond side in hopes of
operantly reinforcing increased activity, but unsuccessfully so.

For the fish, we would like for their apparent anxiety levels to
decrease so that they could resume their previous carefree existence.
For us, we found them to be much more enjoyable prior to the heron
attack.

If anyone has any suggestions about an approach we can take to
bring harmony back to our situation, we would be most appreciative.
Many Thanks in advance.

BA and Missy Finstead

Sorry to hear of the heron attack on your fish.

Here in the UK I've had one or two grey herons take fish from my 1800 litre
pond over the past few years. My fish were, just as you explained about
yours, spooked after the incident. Rest assured the fish will come round to
normal behaviour again. I would just continue as normal as possible with
them - but paying careful attention not to startle them. My fish took around
two weeks to near normal behaviour.

On one occasion a goldfish received injuries from what I can only imagine
was a heron's bill; a clear "V" on each side of the fish's abdomen. Its
scales were taken off and the orange colour went in place of the white skin
underneath. The fish made a full recovery and after about 9 months the
scales and colour had returned.

I have a string line about 10cm above the edging across part of the pond to
discourage herons landing - it seems to have worked so far.

Hang in there, they'll be OK, I'm sure.

Regards, Darren

wrote in message
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We have a 500 gallon pond with an assortment of Butterfly Koi,
Shibunkin, Cat Fish, and Gold Fish--all have names. We did not know
until 2 weeks ago that there are herons in Southern California. We
came home from vacation to find Groucho gone; while we did not see the
attack, there were gill remnants beside the pond, and the next day a
large heron was spotted in our yard. Our neighbors then excitedly
reported that they had seen 2 herons in their yard the previous day;
their joy at the sighting was substantially greater than was ours. The
circumstantial evidence is pretty strong that Groucho lost the heron
vs. fish battle. Anyway, 2 scarecrows and an electric fence seem to
have protected us since then.

The problem now, though, is that our fish have been seriously
spooked. Or at least that is what we surmise. Prior to our vacation,
they were quite active and seemingly fearless. Afternoon is feeding
time, and we could anticipate the fish once they saw us to start
circling furiously in anticipation of their food. Now, they are
profoundly less active, and head for the bottom when they see us. If
we sneak up on them at night, and suddenly turn on the flashlight, we
discover that they are more active than during the day, but then
immediately they hunker down on the bottom until we leave.

In hopes that the problem was something other than psychological,
I tested the water for pH, ammonia, and nitrates--high pH (normal for
us), but all other parameters normal. I exchanged about 20% of the
water (using a dechlorinator) to no avail. We have tried withholding
food in hopes of enticing them to the surface, but their food reserves
and the algae in the pond keep them on the bottom. We have tried
feeding them while standing quietly at the pond side in hopes of
operantly reinforcing increased activity, but unsuccessfully so.

For the fish, we would like for their apparent anxiety levels to
decrease so that they could resume their previous carefree existence.
For us, we found them to be much more enjoyable prior to the heron
attack.

If anyone has any suggestions about an approach we can take to
bring harmony back to our situation, we would be most appreciative.
Many Thanks in advance.

BA and Missy Finstead

When a kingfisher dove in my pond, the fish were really
spooked. I put in a decoy, which the silly bird dove in six
times to try and catch.
It took the fish a long time before they would
come to the surface again. But eventually they were back
to their same friendly personalities.

kathy :-)

I have a similar setup, but have only goldfish. They (or most of them,
that is) have survived a couple of heron attacks. Yes, they do get
spooked after such a traumatic event, but they do return to their
normal behavior in a few weeks, assuming that there are no subsequent
attacks.
I don't know any special tricks, but I just approach the pond quietly
and offer a little food once or twice each day. Eventually, they
should come around to being their old selves again. The bad thing is
that after they get back into their trusting mode, they are once again
more vulnerable to becoming a snack for the evil bird!
Good luck,
Gary