H.dunni cooling help.

[Rodrigo]

Hi, i´m hoping to get some help on wether i should cool my Hynobius dunni group and how to go about it if i should. Sadly, information specific to this species is rare and not fully complete.
I have 5 individuals, 3 of them are aproximately 9,5cm long or perhaps a little less, and have started to develop a more adult look and coloration. The other two are somewhat smaller and retain a more juvenile coloration. Do you think that cooling them has any chance of succesfully getting them to breed at this stage or if it would be benefitial regardless of breeding success? I´m not confident that they are old enough, but i´d apreciate personal experience on how big your animals were when you first started to cool them or succesfully breed them. Should i just leave them at a cool room temp to allow them to keep growing?

Also, in the event that i should cool them, i was thinking of using the fridging method. However i´m reticent and concerned about this method as i´ve never personally used it before. I know of people who have, sucesfully and i have an idea of how it should be done, but i´d apreciate personal experience and information about this as well. I´m particularly concerned about humidity as i know fridges can potentially cause rapid dessication and i´m wondering about how much ventilation should be provided. Also, is it wise to do regular checks on them while they are in the fridge? How long would you consider the procees should take?

Looking forward to hearing from personal experiences or perhaps articles that deal with the specific subject. As i say, information is not abundant. Thank you!

[Chris Michaels]

I think that if some of the animals are quite small, they are unlikely to breed (particularly females) and it's probably best if they are grown on much quicker at (cool) room temperature. Stuff them full of food throughout the winter and next year and then try cooling them next time around. If they can get a little cooler over the winter, that would probably be a good idea, so if they can go next to a north facing window or something that can be left open a crack, that would be good...

As long as you keep the sals in plenty of moss and dampen frequently, they will be OK in the fridge. For this species, you can even leave a cm or two of water standing at the bottom of the tank. Mine used to overwinter underwater to avoid the small amount of frost that got in occasionally. The closer you can get them to 0 deg. C, the better (obviously avoiding freezing). This is something that Henk Wallays advised me of when he gave me my animals and I came to the same conclusions through experience. Cooling to 10C is unlikely to work, 5C or under is better.

The other thing to make sure of is that the containers are light-proof so the newts aren't disturbed every time the fridge door is opened and to provide lots of earthworms throughout, as in my experience H. dunni continues to eat a small amount for most of the winter.

TO breed, the water temperature needs to be quite low, too - around 10C - so you will need to find some way of doing this...perhaps a large drinks fridge with the breeding tank inside.

Hope that helps

C

[Rodrigo]

Thank you, Chris! Much apreciated.
I think you may be right, even if some are changing color and looking more mature it doesn´t mean females will be ready at all. It could be that those are males, even. I´ll keep them at about 14-15ºC during the winter with some colder spells and feed them a lot as usual. Maybe next year :) I was indulging myself in a little wishful thinking :P

I´d like to ask a couple of things anyway, for future reference. How big a container would you recommend? I´m glad to hear they can be kept with a little water in the bottom (that eliminates my concerns about dehydration) which actually makes a lot of sense... Not surprised they keep being ferocious, blood-thristy monsters even during the colder periods, they are such pigs :S
Any ventilation at all?
I´ll have to devise a method to maintain their future breeding tank at lower temps. Possibly insulation and ice bottles? It will probably be close to 10ºC on its own for some time, anyway, so perhaps not much of an effort will be needed.

[Chris Michaels]

I would either do each animal individually in something the size of a margarine tub or use larger boxes for all/some of the animals. They don't have to be huge as long as they are packed with moss so the animals can escape each other easily. It's probably worth moving them to new tubs (pre-chilled) occasionally to avoid build up of waste. As I said, they slow down but don't become completely dormant and can still move surprisingly fast at low temperatures! If you can, it's a good idea to give them a warmer (7C or so) spell in the fridge before moving them to the breeding tank. They are useless at catching food in the water (just as eager, but they are terrible at grabbing and hanging onto anything) so it's worth feeding them up well before moving them to the breeding tub.

Insulation and ice bottles should work as long as the temperature stays at 10 or lower and doesn't fluctuate too much. There are some fancy new aquarium chillers (work like a canister filter) that are relatively cheap compared with what they used to be, which could be another option.

The breeding tank doesn't have to be huge, but don't have any water movement and make sure there are plenty of twigs! You may find that males become more aquatic in the spring, anyway, if they have a bit of cooling. They will breed with some of the blue-white stippling still on them.

All the best

C

[Rodrigo]

Ok, i´m preparing to fridge the dunni and i just want to make a couple of last minute consultations.
The fridge is at 6ºC, and i´ll eventually lower it to 5ºC. I´m uncomfortable with lower temps because i don´t trust my fridge to be consistent...I had some issues with ice in a fridge (although admitedly a different fridge) once and it makes me paranoid...
The male tank is a roughly 5l tank (standard proportions), filled with layer upon layer of moss to a depth of 11-12cm and will have a 2 cm deep pool of water at the bottom. The tank will be covered with a thick dust bin bag to keep it dark. The female container is the same in terms of "furniture" but is just an opaque, black ice-cream container and the layers of moss will only be 6 cm deep at most (should i feel it to the top or leave a small space between the top of the moss and the top of the container?. I thought it´d be better to separate them by gender because the female is a somewhat less aggressive eater.
If i just open the containers and introduce the food, allowing the light in for a moment, is this ok? Should i try to avoid this or is it negligible? The same goes for container changes.
I´m sorry for all the questions and obssesive paranoia...it makes me quite nervous as i´ve never done this before with newts and my experiences with things like fridged earthworms are mixed xD

[Chris Michaels]

Sounds OK to me. I would leave a gap between the top of the moss and the lid, as the sals will come to the surface sometimes. I would also bury some bits of cork bark in the moss to create hollows at different levels - if the moss is nice a fluffy you may not need to, it's just in case the moss compacts too much. I wouldn't worry about a bit fo light getting in, it's just the fridge light turning on each time the door is opened that could cause a bit of stress.

If you throw in small earthworms they will survive if not eaten.

The next important thing is to get the breeding tank cool enough for when you introduce them! What is your sex ratio? If you hav eonly one female, I would only put ther in with a couple of males at the most as they will compete amongst themselves for breeding sites, females and egg masses and can prevent each other from fertilising the eggs properly or can damage the egg sacks causing them to burst.

It's probably worth asking Joost for info, too, as I believe he bred yours (right?) and may have some extra advice...

Good luck!!!

[Chris Michaels]

Also, re ice problems, they are evry hardy - my tank used to freeze over on the durface and all round the sides to a thickness of about 0.5-1 cm and they were fine. They will find pockets without frost so as long as the whole tub doesn't freeze you should be OK.

[Rodrigo]

Thanx, Chris...i´m just so new to this xD
It turns out one of the "males" is almost definitely a large female (large for their current sizes that is). I assumed the one that died to be a female and never got to examine the rest to confirm it, but now that i have, i´m pretty sure it´s 2.2, which is great.
Man, taking these bastards out of their tank was a nightmare...i had to flood everything to force them out and it still took quite a while to catch them!
I have introduced earthworms in the tubs.
I´ll be strong and reduce the temperature progressively. In defense of this fridge, it has been fairly constant during "The Trials" so it´ll probably be ok.
The moss is quite fluffy and i didn´t pack it too much, but if i see it´s getting compacted i´ll introduce the bark layers right away.
I don´t think Joost bred these, i think he acquired them as metamorphs, obviously thinking they would eventually make me happy, of course :P

Thanx again for the responses, Chris, if i succeed at all, you better prepare a tank....

[Rodrigo]

I´m finishing the details of their, hopefully, breeding aquarium and it won´t be long until i introduce them to it. I´m really nervous, man They are looking good i think. The two males are yellow with big cloacae and enlarged heads, and the two females look rather chubby.
Here are a couple of bad pictures. One is with flash so that the colours show, they are amazing! The yellow itself is pretty but the pinkish, almost translucid patches give it an amazing look.
Aaaaaarghhhh....i can´t wait (to be dissappointed when they don´t actually spawn :P).

[Chris Michaels]

Looking good! Just keep the tank as cold as possible, about 5C if possible, and make sure you have water at least as deep as your animals are long, but not more than twice as deep as they are long. I'll be first in line for juvies if you succeed!!!!! They usually spawn at night, so during the day they (particularly the females) may disappear into semi-terrestrial hides; at night the action will begin!