Experiment on hatching the eggs of the Simp magnificus

[stormhawk]

By the way, the disposable containers should be fresh ones bought from the shops. If these were used for packing food and then washed with detergent, it will become deadly for fish use.

The fry die when left in the hatching container too long. This occurs as the peat begins to leach tannins again. As time passes the oxygen levels in the container drop so I usually break another O2 tablet and drop the pieces into the container after I see some fry struggling. This somehow helps.

Changing the water partially in the container also help as the hatching fry can literally give off some ammonia or nitrate since they are also respiring and breathing animals. Such conditions can cause lots of dead fry.

Occasionally these fry are also those that are beyond any help. In this case they are fully developed but have missed their hatching window. Once a resting fry in an egg misses its hatching window, the fry usually loses its ability to swim properly as it is literally feeding off its own body while still in the egg if one misses the wetting stage for the eggs. More often that usual it is the swim bladder that gets affected badly by this problem.

[TyroneGenade]

This time I gather two batches of dead frys.
Left the oxygen tab a little longer than before and forgot to skim the oxygen whitish residue floating on the surface. Found only 4 dead fry.

Question - Would the film on the surface cause some difficulties in air exchange? Found no living frys except 4 dead fry.

Such a film may interfer with gaseous exchange but I suspect something else happened.

Some eggs always die in the peat and some deomposition can take place. This means there may be ammonia present in the water. If the pH is below 7.5 this should not be a major problem as it will be in the form of harmless ammonium. But if you increase the O2 levels then the ammonium can be converted to very toxic nitrite which may of killed the fry.

As of later I've been hatching fry in large shallow tubs (at least 5 x 8 inches with depth about 3/4 inch). I've largely dispensed with peat of any kind and simply toss in the eggs with some peat extract and 1 O2 tab. Then the lid goes on tight so the O2 levels will remain high. This works well.

I have had it once before where I wet some old peat with eggs and got nothing but dead fry. The eggs were old though so the fry may of been week.

At high concentrations O2 can also be toxic but this is unlikely the case here. I think it was far more likely a case of decomposing waste in the peat you wet.

Regards and better luck next time.

[selena]

Hi Tyrone,

Thanks for stepping in.

Such a film may interfer with gaseous exchange but I suspect something else happened

I believed so. After I spooned away, latter batch were doing OK.

Some eggs always die in the peat and some deomposition can take place.

This peat was used the previous night. Had went through many round of hot water to clear away any chemical. Old water (2/3/05) were disposed and new aged water were used.

I have had it once before where I wet some old peat with eggs and got nothing but dead fry. The eggs were old though so the fry may of been week.

Should I throw away this peat, saw a couple eyed-up eggs this morning. Surprisingly is that those fry that I put in the growup container were alive and those that I was too tired to spoon out, could not make it. There is something in the peat that are killing my babies.

Jianyang dear ,

'Nasi Lemak' container was just a description to give others a idea how it look like. I bought 10 set for S$2.50 last Sunday just for this special occasion.[/quote]


Thanks


Selena

[stormhawk]

The peat is a practically decomposing material. So usually most fry don't make it if they are left too long in the tray. Once they are free-swimming they should be taken out promptly.

Collect, dry and bag up the peat soon. If the eyed-up eggs are not hatching its time to bag it up again. Try re-wetting a few days later. Sometimes the eggs seem to be eyed-up but the fry do not wish to hatch out just yet.

Haha, for awhile I thought you actually use those containers that had "nasi lemak" in them. Ok so I was wrong but good to have these containers around. They are good as hatching trays. Just one thing, you should rinse these trays properly. Most of the time they come with an "oily" feel especially if they are new. You need to rinse off this "oily" film before using the containers. This is usually some residue from the manufacturing process and it can poison the fry if it actually leeches into the water column.

[timebomb]

Hi, folks,

I'm not so sure if oxygen tablets really help in the hatching of eggs. A few days ago, I wetted a bag of Simp. magnificus eggs and this time, I included the peat in the hatching container. But I used CO2 instead of O2. Here's a picture of my hatching container with an airline that's rigged to my CO2 gas tank.



After a few hours, there were many fry.



Initially, most of the fry were healthy and they were swimming near the surface. However, those that hatched later were just lying on the peat, apparently too weak to swim. After 24 hours, those that weren't swimming were already dead.

Loh K L

[promethean_spark]

The long dormant period of these eggs probaby gurantees that a considerable number of fry will be over or under-mature. However, going to great lengths to increase the hatch rate may not be in hobbiests best interests because it doesn't help to selectively breed these fishes to be easier to hatch, and that would be a lot more helpful to the hobby in the long run.

Of course, if you're looking at the difference between zero fry and a successful hatch, getting fry comes first.