Krishna Panchami is the twentieth tithi overall, the fifth day of the waning fortnight, sharing the character of the fifth tithi, a Purna or full day linked to the Nagas, the serpent spirits. As a Purna tithi it is read in the panchanga as relatively stable and favourable even within the dark half. The waning Moon is now past its gibbous phase and moving toward the last quarter. Certain regional observances attach to particular dark-fortnight Panchamis, and the serpent associations of the fifth tithi carry across both fortnights. These are the conventions of the calendar tradition, which counts each of the fifteen tithi-numbers once in the bright fortnight and once in the dark, distinguishing them by paksha.
The Naga association carried by the fifth tithi persists into the dark fortnight even though the major public festival, Naga Panchami, is kept in the bright half, and several regional traditions maintain quieter household observances to serpent deities on the waning Panchami as well, reflecting how thoroughly the tithi's deity assignment, rather than the specific festival built on top of it, governs the general character ascribed to a day in panchanga practice. As a Purna tithi the waning fifth is read as comparatively steady even though it falls within the generally less favoured dark fortnight, illustrating that the fivefold classification and the waxing-versus-waning distinction operate as two separate, sometimes conflicting layers of judgment that a traditional astrologer weighs together rather than reducing to a single verdict.