How to feed *Rana latastei* tadpoles?

Rana latastei is a vulnerable frog species that lives in a limited area from Switzerland to Croatia.

My problem is that a couple have decided to leave their eggs in a plastic container full of rainwater outside in my yard:
https://www.inaturalist.org/observations/152129220

If the survival rate in that container is higher than in a pond where there are lots of natural predators (estimates are that only about 1% of the eggs will grow into frogs, most being eaten by fish, birds, and larvae of dragonflies and diving beetles), I am now left wondering what I can do to provide them with enough food. According to what I have found, these tadpoles live on a plant-based diet, becoming ‘meat eaters’ only as adults.

What kind of plant though? Any ideas?

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Get dandelion leaves, pour hot water on them, then wait till they’re colder, give those to toadpoles, each one of them needs 10x10cm space, so make sure they have enough space to grow.

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Algae wafers for aquarium fish would be excellent.
Peas, lettuce, cucumber, carrot and kale would be very good too, especially if boiled.
Don’t overload the water with food to avoid bacterial blooms.
One of the best things you can do for these animals is to buy some liner and build a fishless pond for them.

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Why, yes, of course!! The same fare that my sweetwater fish used to eat!
Splendid, you two have helped me a lot.
Thanks also, Marina, for pointing out the space requirement. Makes sense, too, of course. But I needed my brain getting kicked in gear.
Will now collect as much rainwater as is possible to prepare enough containers in time for when they hatch.

As for the liner, I in fact got two small artificial ponds last year which I was thinking of placing where the rain water reemerges from the ground before it flows off into a ditch, in an attempt to collect and conserve enough for puddles to be used by the dragonflies. Last year they had a particularly hard time because of the drought.I watched a female dipping her abdomen on the plastic base of a former doghouse as if it were water: https://www.inaturalist.org/observations/125227154

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Boiled frozen spinach is common for raising tadpoles in labs. Boiling isn’t because the tadpoles need cooked food per se but to kill pathogens and cultivated greens can have pathogens that can infect/kill tads.

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Thanks! I’ve never kept tadpoles before, so that is useful info.

Indeed.
Buying plants for fishtanks was ruled out because they would likely be fertilized and/or carry payloads that the tadpoles might not agree with.
Collecting plants from some stream in the neighbourhood is equally risky as I don’t know what chemicals may have flowed off from the fields, and besides, several streams are dry and growing grass, not aquatic plants.

So they’ll get a choice of boilled veggies and the odd spirulina wafer now and then.

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some tadpoles will eat “meat” when given the chance! when i raised toad tadpoles they mostly ate boiled greens, but as they got older and developed legs (but were still aquatic) they would occasionally eat mosquito larvae! just about any leafy vegetable will do though (minus things like iceberg lettuce that have few calories), i personally boiled everything so it was soft enough for them to easily consume

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Hi folks,

Would you say it was normal healthy behaviour for the tadpoles to hang out along the rim like that (see last photo)?

https://www.inaturalist.org/observations/155855649

Or is this a sign that the water is low on oxygen? And that a partial water change is in order?

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You need to change water anyway, but they look fine.

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Are they not chewing algae off the surface?

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They do it in my pond too and I’ve also seen it in natural habitats. They eat the calcareous residue at the edge of the water and warm up in the sunlight. Perfectly normal behavior.

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What a fun topic to read. Thanks for sharing and contributing everyone! This topic reminds me of the caterpillars that I gave my leftover raw organic kale last summer.

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Thank you all for making me feel less anxious. ;-) I bet I sound like a first-time parent. :rofl: Well, tadpole-wise I am.

Not changing the water yet because we just had over 100mm of rain over the last week (halleluja!), and a good part of the tadpole water was naturally replaced. I am going to fish out some of the detritus at the bottom, though (leaves, blossoms, dead insects).

My next bout of anxiousness will come as they grow, when I will start fretting about the appropriate amount of food to give them, without overloading the water with nutrients while not starving them either. I will likely have to dig out my water tests from by-gone aquarium days.

I never worried so much with the dragonfly larvae that grew in my old fishtank outdoors. I never fed them (didn’t have to, there were enough insect larvae in the water), didn’t remove the algae (they lived in the thicket at the bottom), and I also missed their emergence.

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A lot of very important nutrition for tadpoles is in that muck at the bottom, especially the animal material. I would leave it.

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Just keep in mind that an inevitable number of these tadpoles won’t make it to maturity. You’re doing a good thing by ensuring so many of these vulnerable frogs will reach the frog or froglet stage, but don’t be too worried by the sight of one or two dead tadpoles every so often.
I’ve always wanted to do something like this, so I’ll be following this journey somewhat closely - you may just motivate me to do something similar for the native amphibians in my area!
Best of luck to you in your endeavors!

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True, makes sense. And I wasn’t going to remove ALL of it!

My reasoning: if I maintain an approximately constant balance in the water:muck ratio, I lower the risk of the entire system collapsing. I am constantly adding to it after all (food) and so do the inhabitants (faeces).

There is no natural in-flow of fresh water (except for the spring rains now, which are a finite source, though – at the moment my yard is a mess, containers full of spare rain water everywhere). As the weather gets warmer, more water will evaporate and the tadpoles are growing too, eating and defecating more. A growing layer of detritus with its bacteria (those will likely become more active and proliferate with higher temperatures, too) will take a toll on the oxygen.

My problem here is that I am using gut-feeling backed by no hard data to determine the appropriate amount of muck to remove.

I am aware that there will be losses. I am also aware that I will inevitably think it’s my fault because I didn’t take into consideration all factors. :-/

When I first discovered those eggs I was both elated and worried. I certainly didn’t volunteer for this! :-D

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Aren’t they cute with all that glitter? :-)

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For a moment, I wondered if it was worth trying to key out that Taraxacum :grin:

:smiling_face: Yes, very adorable, indeed​:heavy_heart_exclamation: