How often should you feed goldfish?

Many feeding problems in goldfish are problems of too much. Goldfish are enthusiastic, tireless beggars, and the instinct to reward that enthusiasm can fill tanks with waste and fish with fat. The routine that works is modest, quick and slightly boring: small meals, quickly eaten, adjusted for age and temperature.

The basic rule

Feed one to three times a day. A common rule of thumb is to give only what the fish clear within a minute or two at each meal; the RSPCA allows as much as the fish can eat within two to five minutes, while the Bristol Aquarists’ Society says food not eaten in two or three minutes is too much. If food is still drifting after two minutes, the portion was probably too large; if the tank is spotless in twenty seconds and the fish are searching, it may have been on the small side. A second widely used rule of thumb is a portion about the size of the fish’s eye per meal, which sounds mean but many keepers find about right for a small goldfish.

For most adult goldfish, once or twice a day is plenty. Three small meals are often given to juveniles, fish being conditioned for breeding and fancy varieties that struggle with large portions. The exact frequency matters less than consistency and portion size; a goldfish fed a modest amount twice a day is likely to be in better shape than one fed a heap once.

Build the diet on a quality goldfish pellet, preferably a sinking one for fancies, and add blanched vegetables, gel food and the occasional frozen treat for variety. Flakes are fine as a component, but they float, which keepers link to surface gulping, and an open tub is best finished soon.

Getting the portion right, and keeping it there

The eye-sized rule is a good starting point and a poor long-term method, because it depends on judging a small amount by eye every single day, usually in a hurry, and judgement drifts upward.

The published figures are not settled: maintenance rates for dry feed run from 0.5 to 1 percent of body weight a day (University of Florida extension) to 3 percent (the Merck Veterinary Manual), split across that day’s meals. Nobody weighs a goldfish, and the range is wide, so treat those numbers as background to the method rather than the method itself.

The method is to measure once and then stop deciding. Find a portion that passes the two-minute rule of thumb over a few days, then keep that amount in a small container — a bottle cap, a quarter-teaspoon, a marked scoop. From then on the portion is a fixed object rather than a daily judgement, which means it is the same on a rushed morning as on a slow Sunday, and the same whoever is holding the tub.

One caveat about the two-minute test. In a tank with gravel, “gone in two minutes” can quietly mean “fell between the stones”, where it rots out of sight and feeds nitrate much as if you had doubled the portion. Two habits fix it: feed in the same spot every time, so you know where to look, and check the substrate there a few minutes later rather than trusting the open water. A bare bottom or coarse gravel makes this much easier, which the substrate guide covers. The same applies to floating pellets that drift behind the filter outlet and sit in the back corner for a week.

Re-check it twice a year, or after the fish grow noticeably. A portion set for a juvenile is not a portion for the adult it becomes, and this is the one direction in which feeding should increase.

Feed when you can watch

Worth making a habit of, because the meal is a useful daily health check and it costs no extra time.

A goldfish that is well shows it at feeding: it comes forward, it competes, it takes food cleanly, and it goes back to foraging afterwards. Many early signs of a problem show up at that moment — a fish that hangs back, that approaches and turns away, that takes food and spits it out, that eats but cannot hold its position, or that is being kept off the food by the others. The healthy baseline page describes what normal looks like, which is the thing you are comparing against.

So feed at a time when you can stand there for two minutes rather than scatter food on the way out. It also settles the portion question: you cannot run the two-minute test if you are not in the room.

When more than one person feeds

A common cause of a badly overfed tank, and nobody in the household is doing anything wrong.

Each person gives a small, sensible pinch. None of them knows the fish were already fed. The fish beg at every approach whether or not they have eaten, because begging is not a reliable measure of need, so there is no signal that anything is amiss. A one-meal tank quietly receives four.

Two fixes, both of which work:

• One named feeder. Simplest, and the one to use where it is practical.
• The day’s food, measured out in the morning. A small container with that day’s portion in it, and whoever gets there first empties it. Nobody has to remember anything, and the tank cannot be fed twice.

What does not work is agreeing on portion sizes, because the problem was never the portion. It is worth setting up before a holiday too — the holiday guide covers handing the tank over to someone else, where the same failure happens with a fish-sitter who would rather err generously.

Juveniles and adults

Young goldfish grow astonishingly fast in their first year, and growth needs fuel. For fish under about 8 cm (3 in), two or three small feedings a day support healthy development, and keepers often choose a pellet or gel food formulated for growing fish. Keep each portion small: three meals on the eye-sized rule, not three heaps.

By the time a goldfish is a year or two old, growth slows and its needs change. One or two meals a day is enough, and an adult diet leans a little further toward plant matter and fibre, which is where vegetables and spirulina-based foods come in. Older, slower fancies such as ranchus and orandas benefit from sinking food fed at their level so they are not outcompeted by faster tank mates.

Feed the body type, not the species

The amount hardly changes between goldfish. The delivery changes a great deal, and this is the table the individual breed pages each state a version of.

The fish	What changes	Why, in keepers’ experience
Common, comet, shubunkin	Restraint, mostly	Finds food instantly and will keep eating
Fantail, oranda, ryukin	Sinking food, sometimes soaked	A folded gut, and air gulped at the surface
Ranchu, lionhead	One consistent spot, and time	A hood over the eyes, and no dorsal fin
Telescope, black moor, celestial	One spot, and patience	Vision may be limited or unreliable
Bubble eye	Slow food, and slow company	A weak swimmer
Pearlscale	Smallest, most frequent meals	A deep, compressed body
Fry and juveniles	More often, not fasted	Growing, with little reserve

The one that catches people out is time. A slow fancy that has not finished in two minutes is usually not being underfed — it is being timed against a rule written for a faster fish. Sinking versus floating food covers the format side, and chasing and bullying the case where a slow fish genuinely is losing out.

Temperature and season

A goldfish’s metabolism follows the temperature of its water. In the 18–24 °C (64–75 °F) range that most indoor tanks sit in, the normal routine applies. As the water cools, digestion slows progressively and goldfish eat less of their own accord; between about 10 and 15 °C (50–59 °F), keepers reduce to one small feeding a day or every other day and often switch to a wheat-germ-based pellet, the traditional cool-water food, which makers call easily digested. Ponds fall to about 8–10 °C (46–50 °F) in winter, and many keepers stop feeding at that point as a precaution, having cut the ration well before.

Warm water is the trickier case. Above 24 °C the water holds less oxygen, and heavy feeding at this point drives up ammonia just when the fish can least afford it. Feed normally or a little less in a heat wave, never more. Our water temperature guide has the full ranges, and feeding through the seasons covers the whole year band by band, including the spring restart and the autumn taper.

Fasting days

Many keepers skip feeding one day a week, and healthy adult goldfish generally take it in stride. A fast day reduces the weekly waste load a little and is a good day to schedule a water change. It is a habit, not a requirement; a fish fed sensibly does not need it, and juveniles, thin fish and fish recovering from illness should not be fasted. If a fancy goldfish tends to float after meals, a fast day followed by a blanched pea is a traditional first step; keepers report that it helps some fish, there is no controlled evidence, and infection is among the causes of floating. Fasting and rest days covers when it helps and when it does not.

What overfeeding does to the water

The fish rarely eats itself to death. What happens instead is slower and quieter. Uneaten food breaks down into ammonia. Food that is eaten becomes waste, which also becomes ammonia, and the filter converts all of it to nitrate. A generously fed tank runs higher nitrate between water changes, grows more algae, and often turns cloudy or smells faintly of ammonia. The fish live in that water permanently, and chronic poor water is behind many of the illnesses goldfish keepers meet.

Over years, a rich diet can cause the same problems it does in other animals, such as fat deposits and fatty liver. A swollen abdomen has several possible causes, and in a well-fed fancy, diet is one of them. Our guide to overfeeding goldfish walks through the signs and the reset, and the water parameter checker will show you what your feeding is doing to the nitrate.

Coming back from months of overfeeding

Common, fixable, and slower than people expect — because the fish recovers faster than the tank does.

Cut the portion and hold it. To what is finished in a minute or two, and then leave it there. The temptation is to taper, which mostly means feeding the old amount for another month.

Expect the begging to go on. A goldfish that has been overfed may keep begging for a week or two, and begging at the glass is not a reliable measure of need — overfeeding goldfish covers why the fish is a poor witness on this question.

The water lags behind by weeks. Nitrate that has been climbing for months comes down over several consistent water changes rather than one, and algae that the surplus was feeding fades slowly after the supply stops rather than immediately. Judge the change by a nitrate trend across a month, not by how the tank looks on Saturday.

Do not fast the fish to compensate. A rest day is a reasonable habit for a healthy adult and it is not a correction — fasting and rest days sets out where fasting genuinely helps and where it is the wrong answer.

And check what it did in the meantime. Months of surplus food usually show up as nitrate, algae and trailing faeces, and sometimes as a fish that tips after meals — constipation and floating upside down cover those.

Signs of underfeeding

Genuine underfeeding happens too, usually in crowded tanks where slow fancies lose out to faster fish, or when a cautious keeper overcorrects. A thin goldfish looks pinched behind the head, with a concave belly and a body that seems too small for its head. Underfed fish may forage constantly, pick at the substrate without pause, and nip at tank mates’ fins, though a fish that begs is not necessarily hungry, so judge by body condition rather than behaviour. Fancies with heavy head growth or upturned eyes, which may see food poorly, are at particular risk of losing weight in a mixed tank.

Judge condition from above as well as from the side. Seen from overhead a healthy goldfish has an even, rounded width behind the gills; an underfed one narrows sharply there, which is easier to see from that angle than through the front glass. A fish that is losing weight over weeks while eating normally is a different problem — sustained weight loss with a good appetite is a recognised sign of internal disease, and loss of condition alongside faded colour is worth taking seriously rather than feeding through.

The fix for genuine underfeeding is rarely more food overall. It is usually sinking food placed at two ends of the tank, feeding by hand at the slow fish’s level, or separating fish that cannot compete.

When a goldfish will not eat

A fish going off its food is often an early signal, and it is worth working through in order rather than guessing.

1. Test the water. Always first. Ammonia, nitrite and nitrate. A loss of appetite can be an early visible consequence of water that has gone wrong, sometimes before anything more obvious shows.
2. Check the temperature. A goldfish in cold water is not ill; it is a fish whose digestion has slowed, and it should be fed less rather than coaxed. The temperature guide has the bands.
3. Ask what changed. A new tank, a new food, a move, a tank mate, a treatment. A fish that is otherwise behaving normally and turns down one unfamiliar food is being fussy, and most will accept it within a few days.
4. Look at the fish itself. Refusing food alongside anything else — clamped fins, sitting on the bottom, laboured breathing, a swollen belly — is a different situation from refusing food alone.

Loss of appetite covers the full list of causes and when it becomes urgent, and feeding a sick goldfish covers what and how to feed a fish that is recovering or under treatment. If the fish is eating but producing long trailing faeces, or floating after meals, constipation is the more likely explanation and it is a feeding problem rather than an illness.

Feeding around water changes, moves and treatments

Small timing points that come up constantly and are rarely written down.

• Water changes: feed afterwards, not before. Feeding first puts waste into water you are about to siphon out, and a fish digesting while a siphon chases it around is having an unnecessarily bad afternoon. Let the tank settle for an hour, then feed — or skip the meal entirely, which is what many keepers do on change day.
• Before moving a fish: do not feed. A fasted fish produces less waste in a bag or a bucket, which matters in a small volume. A day without food beforehand is standard, and the handling guide has the rest of the method.
• The first day in a new tank: do not feed. A newly arrived fish may not be hungry, is usually not settled, and uneaten food in a quarantine tank with immature filtration is the last thing either of you needs. Start the next day, lightly.
• During a treatment: feed less, and check the label. Many medications are dosed against tank volume and some interact badly with a heavy waste load. Using medications safely covers the rest.
• After a fast or an illness: restart small. A gut that has been empty for several days does better with a light meal than a celebration.

Where the rest of the diet is covered

This page is about frequency and quantity. The composition of the diet has its own pages: goldfish nutrition for what a goldfish actually needs, reading a fish food label for telling a good tub from an expensive one, and frozen, gel, live and treat foods for what goes alongside the pellet. Fasting and rest days covers the fast day in more depth than the section above, and feeding fry and young goldfish covers the first months, which are a different problem entirely.

A sample weekly routine

For a mature tank of adult goldfish at normal room temperature, a week might look like this. Portions are small throughout: by the usual rule of thumb, what the fish finish in a minute or two.

Day	Morning	Evening
Monday	Sinking pellets	Blanched peas or spinach
Tuesday	Sinking pellets	Gel food
Wednesday	Sinking pellets	Nothing, or a few pellets for juveniles
Thursday	Sinking pellets	Frozen bloodworm or daphnia
Friday	Sinking pellets	Vegetables
Saturday	Sinking pellets	Gel food
Sunday	Fast day and water change	Nothing

Juveniles get a third small meal at midday and no fast day. In cool water, drop to one meal, feed less often, and consider a wheat-germ-based pellet, the traditional cool-water food. The feeding calculator below will turn your fish, their size and your water temperature into a portion and a schedule you can start with, and sinking versus floating food explains why the pellet type matters so much for fancies.