Start every record with the batch's origins and arrival
A quarantine death means little on its own; it means a great deal next to the same details from other batches. Begin each record with where the fish came from, which species and how many arrived together, and how they looked in the bag — active or listless, thin or well-fed, any visible marks. Note how you acclimated them: floated for temperature, drip-acclimated, or released quickly because a bag was fouling. Record the quarantine tank's setup for that batch — its size, filtration, temperature and whether it had been emptied and dried between occupants or run continuously. When three losses across a season all trace back to fish that arrived thin from one source, or all passed through one continuously running tank, the pattern is standing in your notes waiting to be read.
The timeline of signs, in the order they appeared
Write down what you observed day by day rather than a summary written after the death, because the order of signs is the most diagnostic part of the record — for your own learning and for any vet or experienced keeper you later ask. Note appetite first: eating eagerly, picking, or refusing from the start. Then behaviour: hiding, hovering in the flow, separating from the group. Then the body: clamped fins, spots, film, swelling, rapid breathing. Give each observation its place in the sequence, and record test results for ammonia, nitrite, nitrate and pH on the days you tested, especially the day a fish died. A fish that refused food from arrival tells a different story from one that ate for a week and then faded, and only a timeline keeps those stories apart.
What the batch mates did next
The record is not finished when one fish dies. Note what happened to the rest of the batch over the following days: did they thrive, show the same signs in milder form, or die in sequence? Record whether you extended their quarantine, moved them to the main tank, or held them back, and what happened after any move. Note, too, what the main tank's residents did if the batch had already been introduced. These follow-up lines are where patterns complete themselves — a batch whose mates all stayed healthy points to one weak individual, while a batch that unravelled together points to something they shared, in the bag, the shop's system or your quarantine setup.
Shared threads: equipment, food and handling across batches
Deliberately record the things that stay the same between batches, because a shared thread is invisible unless it is written down. Note whether the same net, siphon or bucket served the quarantine tank without disinfection, whether the same food was offered, whether new plants or decor went in with the fish, and whether the main tank had any contact with the batch through shared equipment. Read several records together at the end of each season and ask what repeats: the same supplier, the same species, the same symptom order, the same gap between arrival and death. KinsLe's Pet Passport keeps each batch's records together in one portable packet, so a season of quarantine notes can be laid side by side and the thread running through them seen at last.