Photographing your goldfish

Photograph it is one of the most repeated instructions on this site. It is on lumps and growths, on bent spine, on torn fins, on ulcers, on cloudy eyes, on swollen abdomen and on a dozen pages besides. What heals and what does not carries a section arguing that the photograph matters more than the diagnosis.

And until this page, nothing explained how to take one.

That is a real omission, because photographing a fish through glass is genuinely awkward — reflections, a moving subject, a camera that focuses on the front pane, and light that turns everything a shade of blue. What follows is the technique, the protocol the rest of the site asks for in fragments, and an accurate account of what an image can and cannot settle.

Why a photograph and not memory

The argument is narrow and worth stating precisely, because it is not that photographs are nice to have.

Human memory is very bad at slow change and does not know it. A fin that tightens over three weeks, a belly that fills over two months, a black patch that spreads by a millimetre a week: each day’s fish looks like yesterday’s fish, and the difference never registers as a difference. This is not carelessness. It is how visual memory works, and it fails hardest on exactly the changes that matter most.

A photograph does not smooth. Two images a month apart, taken the same way, show a difference that no amount of looking would have caught.

The corollary runs the other way too. A great many worried keepers are looking at something that has always been there. Red streaks makes the point directly: compare an older picture, and if the markings were always present, they are anatomy rather than a symptom. A photograph prevents false alarms as often as it catches real ones.

The one to take today

A very valuable photograph of your goldfish is of a healthy goldfish, and by definition it has to exist before you need it.

Signs of a healthy goldfish makes the baseline argument in full: illness in a goldfish is usually a change from that individual’s own normal rather than a match to a list of signs. A fish that always sat a little low is not the same animal as a fish that has started to. Without a record you cannot tell those two apart, and the difference is most of the diagnosis.

So before reading the rest of this page: go and take two pictures of each fish you own, one from the side and one from above, and put them somewhere you will find them. Five minutes, once. Everything below is refinement.

The two angles

Almost all the information sits in two views, and most keepers only ever take one.

From the side is the familiar one. It carries fin condition, body outline, colour, the eye, the wen, and the line of the back. It is what you will compare for torn fins, for ulcers, for wen growth in the breeds that have one.

From directly above is the one people skip and the more diagnostic of the two. It is where a bent spine becomes obvious, where one-sided swelling shows against a symmetrical fish, where a belly that is filling can be compared against the fish’s own width a month ago. The ranchu page notes that the breed is meant to be judged from above; the principle generalises, because deviation from bilateral symmetry is invisible in profile and unmistakable from the top.

Take both. They answer different questions and neither substitutes for the other.

Getting it through glass

The technique is simple and almost entirely about controlling light.

Turn the room lights off. Leave the aquarium light on. This single step removes most reflections, because a reflection is the room arriving at the glass and bouncing back. A dark room has nothing to bounce.

Put the lens against the glass, or as close as it will focus. Contact eliminates whatever reflection survives and stops the camera focusing on the front pane instead of the fish. If your phone will not focus that close, back off slowly until it locks.

Never use flash. It fires into a sheet of glass and returns straight down the lens. If the aquarium light is not enough, put a lamp above the tank shining down through the water, not at the glass.

Wear something dark if you are close to the front. A pale shirt is a light source and will appear in the picture as a ghost across the fish.

Clean the glass first, inside and out, over the area you will shoot through. Algae film and hard-water spots read as texture on the fish.

Shoot square to the glass. At an angle, refraction distorts the body shape, which matters a great deal when the whole point is comparing outlines over time.

Wait rather than chase. A goldfish patrols a repeating route. Set up, stay still, and the fish will bring itself back to the same place. Take a burst and keep the sharp frame — with a moving subject in modest light, that is a numbers game rather than a skill.

Getting the shot from above

The more useful of the two angles is also the harder one, and it has its own technique because you are now shooting through a moving surface rather than through flat glass.

Still the surface first. Ripple is the whole problem: it bends the image and smears the outline you are trying to compare. Switch the filter off for a minute and let the surface settle, and lift out or switch off an air stone if there is one. Turn them back on afterwards, which is easy to forget and is one of the commoner ways a keeper leaves a filter dry.

Remove the lid and shoot straight down. A cover glass adds a second reflective surface and usually carries condensation and salt marks. Shooting at an angle across the surface returns a mirror rather than a fish, because water reflects almost everything at a shallow angle and almost nothing when you look straight into it.

Get your own reflection out of the frame. Standing over an open tank with a lit room behind you puts your silhouette on the water. Room lights off, tank light on, and lean so your head is not between the lamp and the fish.

Wait for the fish to be level and away from the glass. A fish hugging the front pane photographs with a reflection beneath it that reads as a second distorted body, and one tilted even slightly loses the symmetry that is the entire point of this view.

And shoot a burst. From above, a goldfish is moving in two dimensions rather than one, and the proportion of usable frames is lower. Ten frames and one keeper is a normal ratio here and not a sign you are doing it badly.

If a tank makes this impossible — a hood that does not come off, a position against a wall — a shallow clear container is the alternative used at shows, though it is a handling event and handling, netting and moving a goldfish covers why to keep those rare and brief. For routine pictures, through the surface is the right answer.

Light, and why consistency beats quality

This is the part that decides whether two pictures can be compared, and it is worth more than any amount of technique.

Aquarium lighting has a colour. Most tank lights render fish cooler and bluer than daylight, and different lights differ from each other. That is fine — what is not fine is comparing a photograph taken under the tank light against one taken by a window, and concluding that the fish has paled. For pale or faded colour in particular, an inconsistent light source will manufacture a symptom that is not there.

So pick one lighting condition and keep it. The aquarium light with the room dark is the easiest to reproduce, because it is identical every time. Daylight through a window is not: it changes with the hour, the season and the weather.

Turn off any automatic colour adjustment if your phone offers the choice, and avoid filters and “enhance” entirely. A picture that has been improved is a picture that cannot be compared with last month’s.

Same background, same angle, same distance. Photographing the fish against the same section of the tank each time removes a variable you will otherwise mistake for a change in the fish.

Scale, and how to get it into the frame

A photograph with nothing to measure against records appearance. A photograph with something fixed in it records size, and size is what several of the health pages actually turn on.

Use something already in the tank and not going anywhere. A particular stone, the edge of the filter intake, a mark made on the outside of the glass with a sticker. It does not need to be a known length — it needs to be the same object next time.

A ruler against the outside of the glass works, with one caveat that catches people out: it only measures a fish that is against the same pane. A fish two-thirds of the way back photographs smaller, and comparing it against a ruler at the front will suggest it has shrunk.

For a lump, get the scale reference beside the lump, not elsewhere in the frame. Lumps, growths and tumours is built around whether a growth is changing, and a dated picture every month or two with something for scale is described there as a very useful thing a keeper can do.

Dating and finding them again

A photograph you cannot find is not a record.

The file date is usually enough, and every phone keeps it. The failure is not the date — it is the folder with four thousand pictures in it.

Make one album per fish, if you have more than one. Fish are hard to tell apart in a photograph months later, and an album named for the animal solves the whole problem at no cost.

Note the water readings with it when something is wrong, because a picture of a fish and a set of numbers taken the same day are worth far more together than separately. This is the pairing a vet will want, and it is the pairing that makes what heals and what does not answerable.

What a vet actually needs

Different job, slightly different pictures, and worth knowing before the appointment rather than during it.

Finding an aquatic vet covers the practical side of getting seen. On the imaging specifically:

• Video as well as stills. Breathing rate, how the fish holds itself, whether it is struggling to stay down — none of that is in a photograph, and much of it is what a clinician reads first.
• The whole fish, not only the lesion. A close-up of a wound without the fish around it loses position, which is diagnostic.
• Several angles of the affected area, because a raised lesion and a flat one look identical from directly in front.
• A picture of the tank, which answers a dozen questions about setup without you having to describe it.
• The water test results, photographed or written down, from the same day.

Send these as part of the case rather than instead of it. A photograph is evidence, not a consultation.

What a photograph cannot do

The site is consistent about this, and a page recommending photographs owes the other half plainly.

Three specific limits worth carrying:

It does not identify causes. Two very different problems can look identical, which is why the health pages ask you to test the water and describe behaviour rather than to match an image against a gallery.

It does not capture behaviour, which is often the earliest sign. Caring for a damaged goldfish makes the point that a fish sitting permanently in one corner has told you something no photograph will show. Take a few seconds of video alongside.

It does not settle sex, age or breed reliably. Sexing goldfish is explicit that an outline photograph cannot do it; how big do goldfish get explains why a photograph of a large fish can look unremarkable or startling depending on breed; and identifying a breed frequently needs a view a profile shot does not offer.

The whole protocol, in one place

Collected from the pages that ask for pieces of it.

When	What	Why
Today, fish healthy	Side and above, each fish, filed	The baseline everything else compares against
Every few months, routine	The same two, same light	Catches drift nobody notices
The day something looks wrong	Both angles, plus the lesion with scale, plus video	The start of a series
Then daily or weekly	The affected area, same angle, same light	Answers stable, improving or worsening
Before contacting a vet	Add tank shot and water readings	Makes the first reply useful
When rehoming or selling	Side view with something for scale, tank shot	Rehoming a goldfish covers why