A tetra breeding project generates dozens of small facts per batch, and the facts only become knowledge when every batch gets recorded the same way. Give each batch one log entry with exactly eleven fields: spawning date; pair or group; water conditions before spawning; egg location; hatch date; first free-swimming date; estimated fry count; foods offered; water changes; losses and deformities; and weekly size estimate. Eleven fields, completed in that order, for every batch — identical structure is what lets you compare a successful spawn with a failed one months later.
Open the Entry on Spawning Day
Fill the first four fields when the spawning happens: the spawning date, the pair or group that spawned, the water conditions before spawning — temperature, hardness and pH as you measured them, plus recent water changes and feeding — and the egg location, whether scattered among plants, on a spawning mop or on the glass. A worked opening, using only the eleven fields: “Spawning date: 3 March. Pair or group: pair A. Water conditions before spawning: soft, acidic water after two small changes. Egg location: spawning mop. Hatch date: pending. First free-swimming date: pending. Estimated fry count: pending. Foods offered: none yet. Water changes: none yet. Losses and deformities: none yet. Weekly size estimate: not started.” Pending entries keep the structure complete from day one.
Follow the Same Entry Through the Fry Stages
Update the batch's own entry as development proceeds: the hatch date when you first see wrigglers, the first free-swimming date when fry leave the mop or plants, and an estimated fry count at each stage, counted the same way every time — a photograph against the glass, counted from the image, beats a guess through moving water. Record foods offered as they change, from first foods through to crushed flake, and log water changes with their dates and amounts against this batch. One entry that grows with the fish beats scattered notes across a diary, because the whole story of the batch sits on one page.
Record Losses and Growth Honestly
Complete the losses and deformities field without softening it: numbers lost, the stage at which losses happened, and any deformities you cull or observe. A breeding log that records only success teaches nothing, and honest loss figures reveal whether a pairing, a food or a water routine deserves repeating. Finish the entry with the weekly size estimate, taken each week against a ruler taped to the glass or a measured container, so growth curves can be compared between batches raised under different conditions. Slow growth beside a full feeding record points at the food; slow growth beside missed water changes points at the routine — the eleven fields together let you separate those causes.
Read the Log Before the Next Pairing
Before conditioning the next pair, read back across your completed entries and rank the batches by fry count survived and growth rate, then look at what the leading batches share in their water-conditions and foods fields. Repeat the conditions that produced your stronger batches, change one variable at a time otherwise, and let each new entry test that single change. Over a season, the log stops being a diary and becomes the project's memory, showing which pairs breed true, which foods lift survival, and which water routine your tetras respond to. Kept beside spawn dates for every fish you own, that history travels well, and KinsLe's Pet Passport holds each batch record in the same portable packet, so comparisons survive a house move, a new phone or a change of notebook.