High temperatures cause Belly-Sliding

[timebomb]

Hi, everyone,

I'm performing an experiment to find out if high temperatures during egg incubation and at the time of hatching result in more belly-sliders. For this experiment, I'm using Nothobranchius rachovii.

I keep my N. rachovii's in a 150 litre (40 gallons) planted tank. I have about 5 males and 4 females. Here's a picture of the tank:


Behind the rock in the tank is the breeding bowl:


After collecting the eggs, I store the peat in a small plastic tub:


The eggs were collected on the 24th of July this year. Usually, it takes about 8 weeks for eggs stored under temperatures of between 29 to 30C (84 to 86F) to become fully developed. But I took out the tub from the drawer yesterday and my maid, on examining the eggs, said she saw "eyes" and "body". It's incredible how good is Esperanza's eyesight because even with a magnifying glass, I couldn't see "body". Anyway, here's a picture of an egg that is fully developed:


So yesterday, on the 10th of September, I wetted the eggs. 2 weeks earlier, I already had my raising trays on standby. I put lots of moss into each tray and I left the trays under the sun. Here's a picture of my "raising trays" and the "hatching container" (the round tub):


If you don't already know, the best tool for transferring fry from one container to another is a Chinese plastic soup spoon. You can see one in the picture, just beside the round tub. It beats a turkey baster anytime.


About half an hour after wetting the eggs, I saw the first fry. Several hours later, there were many. I usually won't transfer the fry until they are free-swimming. As I had to go to work the next day, I instructed Esperanza to transfer 10 fry into every raising tray the next morning. When I came home from work today, she told me she caught 60 fry. I had expected a lot more but it could be I wetted the eggs a bit too early. Anyway, here's a picture of some of the fry in a "raising tray".


By Singapore standards, it was a cool day yesterday. The thermometer in my wall clock read 29.5 C (85 F):


Over the next few weeks, I'll be monitoring the fry in every tray. In a month's time, I should be able to tell if there are any belly-sliders among them. I'll keep you all posted.

Loh K L

[nonamethefish]

Very interesting! I have no opinions to offer except that is a beautiful tank you are using for the experiment . Do the Nothos lay all the eggs in that bowl?

[TyroneGenade]

Hmm... v. interesting KL. And indeed, what an amazing tank! I must still summarise that article... will get around to it this weekend.

[timebomb]

Joseph,

I can't be certain if the fish lay all their eggs inside the breeding bowl but I find many eggs when I collect the peat. I do believe some eggs are laid outside the bowl and this occurs when the less-dominant males mate with the females whenever the alpha-male isn't looking

With more than one male in the tank, it does not mean every male take their turns with the breeding bowl. Only one male gets to use the bowl and he's the alpha male. He guards the bowl zealously to the point that quite often, he dies from starvation because he's so reluctant to leave the bowl he hardly ever comes up for food.

I don't know if my experiment is going to be a success because I just checked the trays and discovered that in a couple of them, the fry has completely disappeared. There are survivors in most of the other trays though. No signs of belly-sliding yet but it's too early to tell, I guess.

Loh K L

[nonamethefish]

Joseph,
With more than one male in the tank, it does not mean every male take their turns with the breeding bowl. Only one male gets to use the bowl and he's the alpha male. He guards the bowl zealously to the point that quite often, he dies from starvation because he's so reluctant to leave the bowl he hardly ever comes up for food.

Loh K L

Wow I thought only I had that problem. With the kafuensis eventually the dominate male got to the point where he shot himself in the foot and was ousted by one of the lesser males.