Breeding and Egg Development of Hymenochirus boettgeri

Log 2

 by David Cecere

February 4, 1998

Water Hardness:    Soft
pH level:                6.4
Buffering capacity: Moderate to High
Ammonia (NH4):   0 PPM
Nitrite (NO2):        0 PPM
Nitrate (NO3):      35 PPM

21 tadpoles (including Lucky)

The pH has dropped to 6.4 as a result of increased bacterial biology.  I have avoided a partial water
change in case the tadpoles will be affected badly.  They are so tiny and I still haven't been able to find any information about what their ideal water conditions are.  I am using the Neutral Regulator to move the pH toward neutral but it falls again within 24 hours.

February 8

21 tadpoles (including Lucky)

Batch 3 was laid overnight.  I moved approx. 50 eggs into the net.  I'm concerned about the pH level.  It's gone as low as 6.2.  I am going to have to use a different product to raise the pH since the Neutral Regulator isn't strong enough.

February 9

5 tadpoles

I've lost 16 tadpoles!  They seemed fine when I looked at them in the morning but were dead this evening. I have preserved several in alcohol in case I get the chance to examine them under a microscope.  My hunch is that the pH level is the cause.  I read recently that many of the African lakes are alkaline to the level of 7.6-8.2. The adult frogs in the tank seem healthy, but I suspect that the tadpoles are a lot more susceptible to the lower pH than the adults.

February 11

Batch 3 hatched: 20+ tadpoles
2 tadpoles left from Batch 2

I started using a sodium hydroxide solution yesterday to raise the pH.  The solution didn't seem to be having much effect and I was puzzled.  Then it occurred to me that I had used so much of the Neutral Regulator that I now have to overcome the alkaline buffering capacity to get the pH to rise.  I've managed to get the pH to 6.8 but I want to get it to 7.2 and stable.

February 13

Batch 4 laid
20+ tadpoles

I was surprised to see another 100+ eggs laid only 5 days after the last batch.  I collected about 40 and placed them in the net.  I have received Dr. Rabb's paper.  He describes his tank conditions which confirms my hunch: the pH in my tank was way too low.  I have used sodium bicarbonate (baking soda) to raise the pH to 7.6.  The sodium bicarbonate has the additional advantage of adding a lot of buffering capacity to the water.  This should keep the pH stable.

February 16

Batch 4 hatched: 20+ tadpoles
21 tadpoles from Batch 3

Water Hardness:   Moderately hard
pH level:                7.6
Buffering capacity:  High
Ammonia (NH4):   0 PPM
Nitrite (NO2):        0 PPM
Nitrate (NO3):      >35 PPM

The only side effect of the sodium bicarbonate was a clouding of the water for a couple days.  I am testing the pH at least once a day and it has been stable at 7.6.  My next concern is feeding the tadpoles once they're ready for "solid" food.  I have begun culturing fruit flies (Drosophila melanogaster) for two reasons: 1. as an additional food source for my Floating Frogs (Ooeidozyga lima) and as a food for the tadpoles.  I am hoping that the tadpoles will eat the larvae of the fruit flies.  Though Dr. Rabb was successful with brine shrimp larvae I would like to avoid having to culture them since it's messy, consumes a lot of space and is generally a hassle.  Also, I believe that the fruit fly larvae will be a more natural type of food for the tadpoles.  My guess is that in the wild the tadpoles feed on a variety of insect larvae that have hatched in the water.

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