One Entry Per Drop, Written the Same Day
Selective breeding lives or dies on notes taken when the fry arrive, because a month later nobody can honestly say which female dropped or how many there were. Give every litter its own entry on the day you find it: the mother, the tank she dropped in, an honest fry count — 'about forty, five stillborn' beats a tidy invented number — and anything unusual about the birth, such as an early drop after a tank move. Move the entry with the fry: when the litter goes to a grow-out tank, the entry's reference goes on the tank label, so the fish and their paperwork can never drift apart.
Describing Colour So It Still Means Something Later
'Nice red' is useless across generations; you need descriptions your future self can compare. Fix a small personal shorthand and define it once at the front of the log: body colour, pattern type, tail colour, tail shape, and where the colour sits — a fish red only in the tail is a different breeding prospect from one red through the body. Judge and record colours under the same light each time, ideally the tank light the fish live under, because colour read under a shop's light or a window's light will not match. Note the age at which each male's colour arrived and how it deepened, since early and late developers get selected for differently.
Parentage: Certain, Probable and Unknown
Guppies store sperm, so a female can drop fry fathered by a male she has not lived with in weeks — the log has to be honest about that or the whole line's records are fiction. Grade every entry: certain, when the female was raised without males and paired with one chosen male; probable, when she lived with one male but had earlier company; unknown, when she came from a mixed tank. Record which male or males she had access to in each case. Fellow breeders quietly respect an 'unknown' that is labelled as one far more than a confident claim that cannot be true, and your own selections will be sharper for the honesty.
Tracking the Line Across Generations
Give each generation a simple code in the log — the mother's code plus the litter number works — and carry it on every tank label and sale note, so any fish in any tank can be traced back to its drop in seconds. Keep one running page per line: pairings made, litters produced, traits that strengthened, traits that crept in unwanted, such as washed-out colour or fry that grow unevenly. Culling and rehoming decisions belong on that page too, with the reason, because the pattern of what you removed is half of what selective breeding means.
What the Notes Buy You When Fish Change Hands
Fry sold or swapped with a drop record, parentage grade and colour description command more trust — and better homes — than a bag of pretty fish with a shrug. Keep the line page in a form you can share, so a buyer sees exactly what they are getting into. If you ever pause the line and restart it, the notes are the difference between resuming a project and starting over from memory. Notes kept fish by fish like this sit naturally inside KinsLe's Pet Passport, where each guppy's parentage, colours and history stay together in one packet that can travel with the fish to a new keeper.