Courtesy of

ARK - Arizona Rivulin Keepers


The Scheel Letters, No. 17

Resting Eggs

In a previous letter you will find some thoughts on the oxygen problem in the question of Resting Eggs. In order to find out if eggs might be kept for a long time under non-oxygen conditions I collected eggs of several species and stored them in completely water-filled ampoulles (the normal 2 ccm ones) and closed them with cork and parafin. All eggs of Aphyosemion (calliurum, coeruleum, calabaricus, cognatum etc.) died (turned yellowish and turbid) after one or more weeks. When opening the ampoulles the water gave away a strong smell of H2S. But in some ampoulles containing eggs from Cynolebias nigripinnis, C. bellotti, C. melanotaenia, the eggs did not change and still were transparent and apparently alive.

In June my stock of ampoulles was used and one evening I opened two ampoulles in order to use these for mailing of eggs. These ampoulles contained:

1) 5 eggs Cynopoecilus melanotaenia closed for 115 days.
2) 11 eggs cross C. ladigesi/melanotaenia closed for 75 days.

Water in ampoulles was perfectly clear. A certain smell of H2S was traced. Parafin lock was unbroken. Now the 10 eggs C. ladigesi/melanotaenia all contain a hatchable embryo (one egg developed an embryo when in ampoulle and this egg had a dead embryo when I opened the ampoulle). The five eggs from Cyn . melanotaenia still are transparent and possibly alive.

This small experiment might be of great importance in the future mailing of eggs from "real annuals" as lots of eggs might be stored in very small containers and without any air. Also possibly during wintertime such eggs might be mailed by ordinary mail and then the risk of freezing the eggs will be much smaller when mailing eggs overseas.

Possibly also the experiments might guide to a solution of the problem of Resting Eggs in Killies. I certainly know that much more work must be done on this problem before a solution comes into reach. Now I am more sure that the oxygen concentration plays an important role in the development of this phase in eggs.

Resting Embryo

Unlike the case in the 1958 breeding of Nothobranchius melanospilus the (about 50 only) eggs that now are stored on low water in cups do not develop normally giving a hatchable fry after about 4 weeks. In most eggs the development of the embryo stops at the phase "resting embryo" and stays in this phase for rather long time. This is also the case in Notho. "kuhntae" (Griem's stock, possibly "orthonotus"). Here are some data.

Nothobranchius "kuhntae":

Nothobranchius melanospilus: Pterolebias longipinnis: Development of Eggs. Cynolebias bellotti Guevara's stock.