Koi Quarantine Observation Log: What to Record and Why It Matters

By KoiQuanta Editorial Team|Updated Mar 2026

The observation log is how a quarantine-record-for-insurance) becomes documentation rather than just holding fish in a tank. Without it, you're operating on memory. With it, you can reconstruct exactly what happened to each fish over a 42-day quarantine - when a problem first appeared, what you did, how the fish responded, and whether discharge criteria were actually met.

For dealers, this is your liability protection and your buyer documentation source. For collectors, it's the record that tells you whether your quarantine is actually working.

TL;DR

With it, you can reconstruct exactly what happened to each fish over a 42-day quarantine - when a problem first appeared, what you did, how the fish responded, and whether discharge criteria were actually met.
If a fish has been "slightly reduced activity" for 5 days running, that's a trend that warrants intervention - even if it hasn't crossed into obvious clinical signs.
Ammonia at 0.1 ppm for three consecutive days means your filter isn't keeping up.
If you dosed praziquantel on day 6, are you seeing reduced flashing by day 10?
A fish that was eating at 7 AM and dead by 7 PM with nothing observed at 1 PM is a missed observation window that might have caught the problem in time to intervene.

What to Record: The Daily Log Fields

Observation Identification

Date
Time (be specific - "morning" and "evening" is fine as structure, but write the actual times)
Observer name (in a dealer operation, this matters)
Tank/batch identifier

Fish Status

Total fish count - are they all accounted for?
Any deaths since last observation
General group assessment: all active, most active, some lethargic

Behavioral Indicators

Swimming posture: Normal (horizontal, upright) / Tail-down / Listing / Surface-hugging
Fin position: Extended (normal) / Clamped (stress indicator)
Activity level: Normal / Reduced / Lethargic / Stationary on bottom
Flashing/scratching: None / Occasional (1-2 fish) / Frequent (multiple fish)
Schooling behavior: Normal grouping / Isolation of individuals / Erratic movement

Feeding Response

Food offered: Yes / No (skip days are valid and should be recorded)
Consumed: All / Most / Some / None
Fish responding to food: All / Most / Some / None
Feed any concerns noted (fish eating but then spitting out food, etc.)

Physical Observation

Check each fish, or at minimum check every fish in the tank visually within each observation period.

Skin condition: Normal / Excess mucus / Lesion present (describe) / Color change
Fin condition: Normal / Erosion / White edge / Bloody base
Eye condition: Normal / Protruding / Cloudy / One eye affected
Gill observation: Normal bilateral movement / Asymmetric / Rapid / Flared covers
Body shape: Normal / Swollen abdomen / Raised scales
Visible parasites: None / White spots / Gold dust / Visible worms or lice

When you see a specific abnormality, describe it specifically:

"Small red lesion, approximately 1 cm diameter, left side behind pectoral fin, kohaku ID: fish 3"
"Not just 'lesion on one fish'"

Photo documentation with date/time is invaluable and worth doing for any abnormality.

Water Parameters

Record actual numbers, not "looks ok":

Temperature: _____°F
Ammonia: _____ ppm
Nitrite: _____ ppm
pH: _____
KH (weekly minimum): _____ ppm
Salinity/salt concentration (if salted): _____%

Treatments

Product name and active ingredient
Dose (amount per volume: e.g., "2.5 ppm praziquantel in 300 gallons = 2.3 grams added")
Administration method (added to tank water, bath dip, food, topical)
Time treatment added
Water temperature at time of treatment

For ongoing treatments (salt, antibiotic courses): log each dose separately.

Water Changes

Volume removed: _____ gallons
Volume replaced: _____ gallons
Replacement water temperature: _____°F
Salt added to replacement (if applicable): _____ lbs
Medication re-dosed (if applicable): _____ and dose

How to Use the Data

Tracking Trends

A single day's observation tells you the status today. A week of observations tells you whether things are improving, stable, or declining.

If a fish has been "slightly reduced activity" for 5 days running, that's a trend that warrants intervention - even if it hasn't crossed into obvious clinical signs. You catch this by reading across the week, not just today's entry.

Water parameter data across a week tells you whether your filter is handling the bioload or struggling. Ammonia at 0.1 ppm for three consecutive days means your filter isn't keeping up.

Identifying Treatment Response

After each treatment, look at the observations that follow. If you dosed praziquantel on day 6, are you seeing reduced flashing by day 10? If not, the treatment may not have worked - maybe dosing error, maybe resistant parasites, maybe wrong diagnosis.

Document specifically which treatments were given, and compare behavioral observations before and after. This is how you know whether your protocol is working.

Discharge Criteria Tracking

Discharge requires specific criteria to be met (typically 14 clean days, all fish eating, no signs, water stable). The observation log is how you verify those criteria against the record - not against your memory.

KoiQuanta tracks discharge criteria automatically against the observation data you've entered. On paper, you go back through the log and check each criterion manually.

Legal and Customer Use

If a customer contacts you three weeks after purchase saying a fish died of KHV, your quarantine observation log is your defense. It shows what you observed, what you treated, and that the fish met discharge criteria when it left.

If there's no log, it's your word against theirs.

Log Formats

Paper Log

A pre-printed form with fields for each of the above categories works well. Date the top of each page, staple pages together per batch, file in a physical folder organized by quarantine batch.

Pros: works without power, no learning curve, easy to customize

Cons: can be lost or damaged, hard to compile into buyer documentation, no automatic calculations

Spreadsheet

A spreadsheet with columns for each observation field. One row per observation event.

Pros: easy to graph trends, can calculate averages, can filter by date

Cons: doesn't prompt you to observe, requires manual calculation for dose math, not purpose-built for this workflow

KoiQuanta

Purpose-built observation logging with scheduled prompts, automatic dose calculations, discharge criteria tracking, and buyer documentation generation. Every entry is timestamped and associated with specific fish and tank profiles.

Pros: prompts observations, calculates doses, generates buyer packs, maintains audit trail

Cons: requires device with internet access, subscription cost

FAQ

What is the minimum a quarantine observation log should contain?

Date, time, fish count, behavioral summary (eating / not eating, normal / abnormal behavior), any clinical signs, water temperature, ammonia, and nitrite readings. Any treatment administered with product name, dose, and method. This is the floor. A complete log also includes pH, physical observations per fish, and water change records. The more detailed your log, the more useful it is when you need to diagnose a problem or defend a decision.

How often should I update my quarantine log?

At minimum once daily, twice daily during active quarantine. Morning and evening observations give you a complete picture of the day. A fish that was eating at 7 AM and dead by 7 PM with nothing observed at 1 PM is a missed observation window that might have caught the problem in time to intervene.

Do quarantine logs really matter for hobbyists or just dealers?

They matter for anyone who cares about their fish. For hobbyists, the log tells you whether your quarantine was actually working, helps you spot problems early, and gives you data to troubleshoot if something goes wrong. The discipline of writing things down also forces you to actually look carefully twice a day rather than just glancing at the tank. That observation habit has saved more fish than any medication.

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Sources

Associated Koi Clubs of America (AKCA)
Koi Organisation International (KOI)
University of Florida IFAS Extension Aquaculture Program
Fish Vet Group
Water Quality Association