November 09, 2004

Fish suicide and fish waste as fertilizer...

In today's Pond Q&A, we have quesions from as far as Australia
and New Zealand...

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Question #1>

Hi Brett,

I'm from Sydney N.S.W., about 18month ago I built a pond
3mtrx1mtr.x 40cm deep,with submergeble pump and filter ,pump
running 24hrs into a stream and back to the pond ,in the pond a
placed some water lilies and other surface floating green just to
protect the fish from preying birds.

when the pond was ready, I placed 8 fish (a mixture of carpand
goldfish) and they seem to be very happy breeding (at the moment
they have multiplied to 40)

The problem I'm facing is that the fish once they grow to about
20cm (8inch)long they seem to jump out of the water and land
outside the pond and when I found them they dead . do you know
what cause them to commit suicide?

Regards Mario



Hi Mario,

There are really to common causes for airborne escape attempts by
your fish. The first, is that there is something in the water
that they don't care for. Whether it be toxins, or elevated
Ammonia / Nitrite levels... fish will sometimes try to 'escape'
when their environment is too stressful or less than ideal. This
could explain your problem, because if it only happens when the
fish get larger (and pollute the water more), they might be over
contaminating our small pond and producing too much toxic Ammonia
or Nitrite. I'd suggest a good biological filter.

The other common cause for this, is if perpahs you have a return
line in the pond, directing a strong current sideways in the
pond. KOI often like to play in these currents, and sometimes
act like Salmon swimming upstream. On occasion, they get carried
away, and can leap out of the pond.

I lost my biggest and favorite koi (of course) just two months
ago, when I had turned off my waterfall and instead directed the
flow to my side return line. The fish loved to play in the
current, and sometimes swam so hard into it - that they left the
water. In this case, 'Big Red' as we called him, wound up
leaping right out of the pond 'free-willy' style and we found him
15 feet away from the pond later that evening. Now he's buried
on the island in the middle of the pond..

Nobody said KOI were the smartest creatures, they're just pretty
to look at...


Question #2>

Hi, A Q/A for you.

I'm from New Zealand, and we are going into our summer. I have a
question about getting rid of aphids on lily pads in the fish
pond. I am wanting to spray a very small amount of a systemic
insecticide used for roses on the pad, but well away from the
water. Would this work without causing harm to my fish?




Welcome from New Zealand..

Be very careful when spraying ANY type of chemical insecticide on
or near your pond. Pond fish are very sensitive to this, and
even a small amount of Pyrethrin or Permethryn can be very toxic
to fish. So when spraying roses or other plants nearby, always
be mindful of the wind and/or potential run-off of chemicals into
the pond.

In your case, I woulnd NOT recommend spraying the lily pad with
insecticide if you plan on putting it back in the pond.

There are some products, like one called Bladerunner, which are
all natural and are made up of ground up / powdered sea shells,
and that you can spray directly onto the lily pad safely. The
sea shell particles will actually cut open the exoskeleton of the
aphids, and they will dry out and die. See if you can find this

Hope this helps.


Question #3>

Could you please help me answer this question.

Is dirty pond water a good fertiilzer for my roses and other
plants? I figure that since my goldfish is always releasing body
waste, my pond water would be excellent fertilizer for my roses
and my other plants.

Is this correct?

I was going to use about 1/3 of my pond water every week to water
my garden.




Stan - YES!!

Pond water, and particularly your 'waste' water, is Excellent
fertilizer... Better than you can buy in your local garden
center. If you doubt me, try watering your favorite tree or bush
or shrub with pond water for one month, and see if it doesn't
outgrow everything around it substantially.

So yes, it's true. Fish crap is actually good for something.
Just don't share your 'secret' with anyone, they'll think you're


Happy Pondkeeping!

Brett Fogle
MacArthur Water Gardens

Posted by bfogle at November 9, 2004 07:02 AM