Rivulus tenuis Rio Papaloapan

[stormhawk]

Understandably there has been more than one thread on Rivulus tenuis, but seeing that the eggs that I have are of another population other than Tacotalpa, I thought I'd post the images of the eggs up.

Judging from the look of the eggs, how many more days do you guys/girls reckon that the fry will start popping out? 10 eggs were sent and I counted 6 surviving eggs. The eggs are quite large and from what Kee Hoe has told me, the fry should be able to handle BBS at birth, which makes things alot easier.



They resemble miniature golfballs to me.

[Thread Title Edited : Spelling Error for Papaloapan]

[stormhawk]

Don't have any hatchlings yet but the fry in the egg on the left just wriggled in its egg!

[RonWill]

If the embryo looks good and ready to pop, you can also trigger hatching by daily 100% change of incubation water.

If you feel distressed, force hatch

[jbulterman]

My favorite way of hatching overdue Riv eggs including the Pap. is to put the eggs in a plastic film cannister, fill one third with water, put the cap on and tape it to prevent leaking and put it in a front pocket on the way to work. When I get home from work, the fry are usually swimming...

JoeB

[RonWill]

Hey Joe, glad you could join us. Trust everything is well with you and that the TDS meter is still ticking?

I've been collecting some good eggs from Rivulus cylindraceus 'Al Castro' and when dark, developed fry refused to hatch, I blow cigarette smoke into the bag and leave it. At least now, I don't get to wet my pants! (most of my T's don't have pockets! )

[stormhawk]

Thanks Ron, apparently the water changes are working. The fry are wriggling within the eggshell at regular intervals or when I happen to touch the container.

Joe, that method sounds familiar. I think KL mentioned this on the main site previously. Nonetheless, if the water changes fail, I suppose doing this would be better than doing the funky chicken.

My cylindraceus have failed to produce any good eggs after 1 year. I'm still thinking why they're not spawning. Probably because I keep the 6 of them together in a single tank.

[whuntley]

I've been collecting some good eggs from Rivulus cylindraceus 'Al Castro' and when dark, developed fry refused to hatch, I blow cigarette smoke into the bag and leave it. At least now, I don't get to wet my pants! (most of my T's don't have pockets! )

It's probably not the smoke. I have blown my breath over a shallow Petri dish of eggs to increase the CO2 to force the hatch. I have also encouraged a shoe-box of reluctant Notho eggs by taking an airstone into it attached to a DIY CO2 generator (yeast and sugar water). Raising the CO2 just a tiny bit seems to encourage them to hatch.

Wright

PS. Wish I still had those "Al Castros." They are pretty. One interesting European variant on the name was "El Castro." I guess it is, at least, phonetically nearly correct in most romance languages.

[keehoe]

I've been collecting some good eggs from Rivulus cylindraceus 'Al Castro' and when dark, developed fry refused to hatch, I blow cigarette smoke into the bag and leave it. At least now, I don't get to wet my pants! (most of my T's don't have pockets! )

It's probably not the smoke. I have blown my breath over a shallow Petri dish of eggs to increase the CO2 to force the hatch. I have also encouraged a shoe-box of reluctant Notho eggs by taking an airstone into it attached to a DIY CO2 generator (yeast and sugar water). Raising the CO2 just a tiny bit seems to encourage them to hatch.

Wright

PS. Wish I still had those "Al Castros." They are pretty. One interesting European variant on the name was "El Castro." I guess it is, at least, phonetically nearly correct in most romance languages.

Wright, just for your info. I did that with great success with Lampeyes species. Pulling airhose out of the CO2 tank seems too much of a hassle to me. So i use sugar yeast solution to generate CO2 for my mini-planted tank and use that to force hatch lampeyes egg send by chuck few months back.

[stormhawk]

Finally, 5 fry hatched out of 10 eggs sent, induced hatching via CO2 (my bad breath.. ) and some pretty violent shaking.

Another 3 eggs still refusing to hatch. I suppose I'll just have to force-hatch the remainder too.

[keehoe]

5 fry, 3 more eggs to go. What happen to the other two that make up to 10?

[stormhawk]

Probably rotted off during shipping. At least 5 fry out of 10, that's a 50 % hatchrate. Good enough for me, given that the amount of peat the eggs were in was very very little. I learnt something about shipping Rivulus eggs because the method the seller used was very simple, yet effective.

[RonWill]

...learnt something about shipping Rivulus eggs because the method the seller used was very simple, yet effective.

Sheesh... need I ask how? Please elaborate.

Jian Yang, if I can't get fishes over, I'll ship the damn eggs!!

[stormhawk]

The main issue is to ensure that the peat is super moist. He packed the peat in a small ziploc bag, taped on 3 sides with scotchtape, and then wrapped with a small piece of kitchen roll paper that should have been quite moist. Then its bagged in a larger ziploc bag and placed in a small makeshift box made from thin styrofoam. This is then placed in a padded envelope and mailed as usual.

It was quite flat when I received it. Given that I got 8 out of 10 eggs, I'd say this was an excellent way to receive it.

I didn't take photos of the stuff but lets just say the small ziploc bag is roughly 6cm x 5cm and the larger ziploc bag is roughly 9.5cm x 7cm. The larger one was taped at some sides to make it a good fit with the smaller ziploc bag.

[stormhawk]

Quick update. Out of the original 5 fry from the first batch, I found a single survivor today and its already quite big. Dang.. must have munched on his siblings..

Oh well, received another batch of tenuis eggs plus some Riv. hartii Isla Margarita eggs from the same person about a week later. Boy was I surprised. Out of 13 tenuis eggs sent, I had 11 good eggs. 1 egg caught fungus during water incubation and I had 9 fry hatch out. So that brings the total for tenuis to 10 fry. Oddly enough I found two fry which had a bent spine. I don't think they'll survive but hey, its worth a try.

For the hartii, I received 10 eggs, of which 9 survived the trip. Today I found 8 newborn fry in the container after I did a force-hatch earlier. One fry still refuses to hatch out.

The newborns have just gotten a fresh meal of walterworms and have full white bellies to prove it. I'm happy as a lark today.

[Scott_sg]

I know this is slightly off topic, but I have noticed I get much better hatch rates from peat that is shipped more on the wet side. It is just speculation, but I think the wetter peat has better thermal mass, and probably also provides more protection for the eggs with any radiation the postal systems use.

Just something I have noticed.

Scott.

[jbulterman]

When I have Riv's and am not getting eggs and the fish are old enough to spawn, I separate the males and females for about a week and feed each normally. On the weekends I place one male and one female together with a mop in a tank with two inches of water. If they are of spawning age, this method has never failed me; within a day I have eggs. Then I separate them again for the week and then it's fun times on the weekend again. I think it was Bill Gallagher who told me to do this when I was having trouble and was new to Riv's. I use this method for the
Riv. ten. "Pap"

[stormhawk]

I know this is slightly off topic, but I have noticed I get much better hatch rates from peat that is shipped more on the wet side.

Hi Scott,

Your theory does have a basis actually. I was thinking the same thing too, after seeing how successful these Rivulus eggs were sent to me from Europe.

Joe,

Thanks for the tip. I suppose I need to separate my cylindraceus from each other for a few days and then do the new re-introduction. I did get some eggs when I shocked them with a 90% water change but they are rather unwilling to give plenty of eggs like they're supposed to.

[stormhawk]

Thought I'd post this up. Of the initial 5 fry, I'm left with one, and boy is he growing fast. Here's a pic of the little fella, now able to handle whole tubifex worms.



Pardon the blurriness, isn't easy to close up on a young and shy Rivulus fry.

[keehoe]

JY, my "takotalpa" just hatched. So back to egg, fry status.

[stormhawk]

KH, sorry I forgot to update the census, will do so soon.

Anyway, got some new pics of the critters, here's a shot of the same fish in my previous post. He/she has grown alot on a diet of tubifex worms.



Anyone care to guess what gender it might be? I'm thinking its probably a female though hopefully it turns out to be a male..

Plus, a shot of 2 week old Riv. hartii Isla Margarita fry.



Guess what? I never fed them any daphnia or BBS all this while. They were taking walterworms for the first week or so and then I tried giving live tubifex.. and they're eating them!