Question
Hi Robyn,

My name is Brian Rossini and I have a question about death of tadpoles in my new pond.

I constructed a cement pond and surfaced it with Surecoat mixed with acrylic admix.  The pond is 5'x7' by 3.5' deep.  A little curve to one of the sides gives me an estimated 700-800 gallons.  There is a pump pushing water from a filter on the bottom up 3.5' from the surface of the water into another surecoat sealed basin that drops down into three more little (1.5'x1.5') pools before dropping 1.5' into the main pool.  There seems to be quite a lot of aeration from this.  The waterfall is pumped with 1200GPH and runs for about 15 hours per day.  This I filled up 6 days ago on a Saturday.  I've added goldfish, tadpoles, a newt, water hyacynths, a crawdad/crawfish?, assorted backstroking bugs, and some dragonfly nymphs.  All these were gathered in a stream in the hills above Santa Barbara, CA.
   The outside air temp has been about 85-90, humidity 65-90% averaging 75%.  I have not tested water chemistry and will take recommmendations if you have any there.

The next day (Sunday) I bought 8 goldfish and they are still doing fine.  The following day (Monday) I collected tadpoles (about 60) and introduced them along with a few rocks and some of the moss that was growing on the rocks that were in the stream I gathered them from. On Tuesday I gathered about 100 small mosquitofish and 1 crawdad from a different stream and introduced them.  On Wednesday I gathered about 50 more tadpoles from the first stream and introduced them to the pond.

So...
Eight 1.5" goldfish
One 5" crawdad
One hundred 3/4" mosquitofish
One hundred 10 1" tadpoles, at varying stages

The water is a little bit green, but not terribly green.  There are still mossy clumps at the bottom and that is what I assume the tadpoles are mostly eating.

Problem: There have been 3 tadpoles within the past 24 hours that I've seen dead on the bottom, there have been 2 that i've seen dead floating (and looking bloated), and there are currently 5 on the surface of the pond that are alive but are looking very bloated and floating and seem like they are going to die.  They do wriggle and squirm madly for a few seconds when picked up, but are so bloated that swimming down into the water is impossible.

Let me know what additional information you might need and I'll gladly provide it.

Thanks,

Brian


Answer
I'm not familiar with the coating that you used for your pond so I can't say if it is totally safe or not.  Is it sold for pond use?  I'd have to look it up (no time now).

You should run your pump all the time especially overnight when the oxygen dips down.  Good aeration like you have is good in this horrible heat.

You should test your pond water for pH, hardness, ammonia, nitrite, nitrate, and oxygen to know your normal values and target any problems.

Crayfish may eat small fish.  The mosquito fish may become nippy and/or overly prolific.

You may have put too many tadpoles in there not just room wise but as far as food goes.  Tadpoles can eat algae but also fish foods. Bloating could indicate a bacterial or fungal infection.  This usually kills some tadpoles in many batches.  I suggest adding pond salt to the pond (use half their suggested dose for ponds with plants, you don't want to overdo it).  Also, check that your pH and ammonia are okay.  The tadpoles may have suffered some shock from being caught and then going to water with a different water chemistry.  You have good aeration and presumably filtration but the good bacteria aren't fully established.  Tadpoles do better in established ponds.  Hopefully, things will turn out fine!

Robyn
fishpondinfo.com