Ultra-weak, non-termal photon emission is universal feature of living organisms and plants. In our experiment the fine structure of optical radiation emitted by the loach fish eggs is studied. It was shown earlier that such radiation performs the signaling between the distant fish egg samples, which result in significant correlations of their growth. The optical radiation of biological sample was measured by the cooled photomultiplier in photocurrent regime, it was found that the main bulk of radiation is produced in form of short-time quasi-periodic bursts. The analysis of radiation temporal structure indicates that the information about egg age and growth is encoded via the values of time intervals between neighbor bursts with the height higher than some fixed level. The applications of such biological radiation in medical diagnostics and biotechnology are considered.