November 5, 2013
I am looking, probably in vain, for any information on raising Empire Gudgeon fry. I have an adult reverse trio in a temporary tank with some M. ansorgii and I'm pretty sure they have spawned. Twice.
I have no delusions about fry survival. M. ansorgii are hunters and have already eaten any fry that hatched, which means I can't pull them out, which is probably irrelevant given the conditions needed for the fry to survive more than a week.
I am, however, going to be putting together a setup for attempting to spawn these and raise the fry.
I live in the US, which seems to be a hindrance in getting a lot of the things I need in order to even attempt this. For instance, ciliate organisms. I have never come across anyone selling them in the US. Ever. The odd oyster larvae that the fry apparently feed on in the wild - never seen them before today, and this was from me following a link to a place in Canada that sells them. I have an email in to that company to see if it's possible for them to ship to me.
My plan, at present, is to set up a 10 gallon aquarium with some kind of filtration, started at a mildly brackish gravity. I plan to leave the light on this tank for several months, to get a healthy algae population and therefore, hopefully, a large population of microbes. I might even add a piece of live rock from my opae ula tank, which has a ton of green algae on it.
However, I am looking for information on the natural environment of the fry. I know they are found in brackish estuaries. What I can't seem to find any info on, is the microscopic organisms that live there, the algae that lives there, etc. I also wonder what type of filtration would be best - I am thinking a hamburg filter with a hugely oversized air pump powering it, to hyperoxygenate the water without any pieces that would harm the fry. The filter wall turned algae scrubber would also be a great home for microorganisms.
I understand that these were successfully bred and raised in a pond in Japan somewhere... does anyone have access to the article, preferably in an English translation (I don't speak Japanese) that they would be willing to send me?
If the oyster larvae I was reading about are indeed the larval fry's primary food source, it seems their size is 50 microns. Would there perhaps be another live food that occupies the same section of water and would bump into the gudgeon larvae, that might be an easier-to-find substitute?
In general, any information anyone has on this topic would be much appreciated. I don't expect to get many survivors, but I don't think that at least getting a few is out of the question.
July 24, 2010
November 5, 2013
Graham Ramsay said
They are very easy to spawn and you get thousands of eggs every few days. I tried lots of ways of raising the fry. Different water depths, temperatures, filtration, salinity and all types of foods - green water, rotifers, mud from rock pools etc. etc.
The best I did was 10 days.
Oh wow. Never in my wildest dreams did I think you'd ever see this, Graham. I didn't even know you were a member here. LOL!
Do you know the micron size of the foods you were trying? I was reading about your methods last night (earlier today for you Brits :P) looking for inspiration on things to try. I came across a product called Troch-feed (oyster larvae initial stage) that are cryopreserved and probably very expensive and hard to find. But apparently this is one of the feeds the gudgeon larvae would have in the wild, they also swim around the same way as the gudgeon larvae. The ones I found are size 50 microns. Reading up on someone who is working on captive breeding in Australia, he suggests a first food size 10-20 micron and smaller and apparently has a method for culturing these foods. Hopefully he will contact me with instructions on how to do this, as I've never tried raising such small ciliates before. My hope is that the ciliates from this culture will be able to sustain the fry until they're able to accept larger food. If it doesn't work, all I've lost is time. I already have the gudgeons and most of the equipment necessary to do this.
I also wonder, Graham, how you transitioned the larvae to brackish water, and the approximate gravity you kept them at?
I wonder if there is a way to find out the specific gravity of the estuaries where they're found in the wild.
July 24, 2010
The smallest grade food I tried was something called oyster relish which has particles down to 1 micron. Some of the other stuff I tried like Nannochloropsis & green water is also really small. Small enough even for these.
They were certainly eating something as unfed fry always died after 3 or 4 days. I think it may have as much to do with environment than food.
November 5, 2013
Yes, I will definitely have green water and infusoria in with them.
I wonder, did the oyster relish have enough unsaturated fatty acids? Apparently that's a big thing with these fry, and something most of them spawned in captivity miss out on in their diet.
I hope to be able to find a specific gravity reading on the areas the fry are found in at the estuaries. It may be that salinity is as big an issue as food.
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