School cohesion is the headline of a rasbora entry
A harlequin rasbora diary should judge the school before the individual, because this species reads its safety from the group. Note how the fish hold formation through the middle water: a settled school cruises loosely together and regroups within moments after a shadow or tap, while an unsettled one fragments and stays fragmented among the plants. Count the school weekly, since harlequin rasboras kept in shrinking numbers grow timid, and a diary that quietly records the total dropping explains rising shyness better than any behaviour note alone. Name any individual persistently outside the formation, hovering head-down or low near the substrate.
Copper colour and the wedge marking
Colour notes for a harlequin rasbora should describe the coppery body tone and the dark triangular wedge on the rear flank, because both fade in step when conditions slip. Write whether the school glows warm and metallic under the light or looks washed and silvery, and whether one fish is paler than the rest, which separates a group-wide environmental dip from an individual problem. Note males looking slimmer and brighter when displaying to females, a normal brightening worth recording as a positive. Comparing the same description week to week, ideally with a quick photo under the same lighting, turns a vague sense of fading into evidence you can act on.
Feeding in open water and daily activity
Feeding entries for a harlequin rasbora should record confidence, not just consumption, since these mid-water feeders show stress by refusing to rise for food. Log whether the whole school came up to take flake or micro food in the open, how quickly they settled afterwards, and whether any fish only snatched food at the plant line. Note spawning behaviour if you see it, as harlequins lay eggs beneath broad leaves, and record leaf plants added for that purpose. Pair each entry with water test results and temperature, because this soft-water schooling fish colours and behaves best in stable conditions, and the diary should prove stability rather than assume it.
Individual signs to pull out of the school picture
Within the group notes, a harlequin rasbora diary still needs individual detail for the fish that breaks ranks. Describe clamped fins, a rapid gill rate in a resting fish, white speckling, fuzzy patches, or rubbing against plant leaves and wood in plain words with a date. Note injuries after any tankmate scuffle and whether the fish rejoined the school by the next check. Record new arrivals and how the established school treated them, since a newcomer hovering at the edge for one evening is normal while one still excluded after a week suggests the group size or layout needs attention.
When rasbora diary notes should trigger advice
A harlequin rasbora entry should prompt advice when several fish fade together, breathing quickens across the school, a lone fish wastes or develops spots, or the group stops feeding in open water after a change you cannot identify. Bring the school count, recent water results, and the dates signs began when you contact an aquatic veterinarian or seasoned fish adviser, since schooling species are assessed as a population. Act promptly if breathing is laboured rather than waiting for the next weekly note. Keeping each week's rasbora record in KinsLe's Pet Passport preserves that school-level story in a form someone else can quickly understand.