A fry growth record is useful when it explains growth, not merely reports it. Any keeper can write that fry reached a given size by week four; the record that helps with the next batch shows which food, which water routine and which losses produced that size. Use the same fields at every entry: batch identity and hatch date; food type and particle size at each stage; number of feeds per day; water change volume and frequency; size estimate for the batch each week; and losses since the previous entry. Keep those fields identical from the first entry to the last, because a record that changes its own format halfway through a batch cannot be read as one story, and it cannot be set beside the record of the next batch either.
Food and Feeding Fields That Explain Growth
Record food type and particle size at each stage, with the date of every change. Fry growth often turns on timing: a batch moved up to a larger food a few days early can stall while mouths catch up, and a batch kept on tiny food too long can grow slowly despite eating eagerly. Writing the stage changes down lets you see that pattern in your own tanks rather than debating it from memory. Note the number of feeds per day beside the food, since the same food given twice daily and given four times daily is not the same rearing method. If you feed more than one food in a stage, list each one rather than summarising, because a later comparison needs to know whether the batch that grew faster was the one receiving the richer item or simply the one fed more often.
Water Changes and the Weekly Size Estimate
Fry foul small volumes of water quickly, and growth responds to how steadily that load is removed. Record water change volume and frequency in plain figures: how much came out, how often, and whether the replacement water matched the tank temperature. A batch that grows well on small daily changes and a batch that grows well on larger changes every few days are both useful results, but only if the record says which was which. Take the size estimate for the batch each week the same way every time. Photograph the fry against the same background and beside the same scale, or net a small sample into a shallow container and estimate against a ruler, using whichever method you chose at the start for the whole batch. Give a range as well as a typical size, because the gap between the larger and smaller fry is a finding in itself: a widening gap warns that some fry are being outcompeted and may need grading into a second tank, and that decision belongs in the record too.
Losses, and Comparing One Batch With the Next
Enter losses since the previous entry at every sitting, including entries where the figure is zero. A run of zero entries followed by a sudden loss reads very differently from steady small losses, and the two patterns point towards different causes: an event in the first case, a chronic shortfall in the second. Note anything else that changed in the same interval, such as a filter clean, a move to a larger tank or a new food stage, so a loss is never left floating without its context. When the batch is grown, read the record as a whole before you change your method. Compare food stage dates against weekly size, compare water change volume and frequency against losses, and carry one change at a time into the next batch so its record can judge that change cleanly. A record kept this way turns each spawning into guidance for the next one instead of a fresh guess. Pet Passport through KinsLe keeps each batch history filed by date, which makes that side-by-side reading a quick job rather than an evening of searching.