Fish aftercare guides for koi keepers, pond owners and aquarium families
A large koi can return enough ash for a small urn, while a betta may return almost nothing. These in-depth guides start from that honest fact and help you plan a goodbye that suits the fish you actually kept.
By the Fish Cremation & Memorial Services editorial team · Updated September 24, 2026 · 4 min read · Sources
- Written for koi, goldfish, bettas and reef fish
- Straight answers about tiny amounts of ash
- Sourced figures and gentle next steps
Finding the right guide
Which fish aftercare guide should you read first?
Start with the question that's keeping you up. If you're wondering whether cremation is even worth it for your fish, read the ash yield guide first, because the answer depends almost entirely on size. If the arrangements are already made and you're thinking about remembrance, go straight to the marker, memorial or ritual guides.
- [How much ash does a fish leave?](/guides/fish-symbolic-ash-yield) A size-by-size look at what comes back from a koi, a pond goldfish or a tiny tetra, and what a token return means.
- [Pond-side markers after koi loss](/guides/pond-side-markers) Stones, plaques and plantings beside the water, placed so they don't upset the pond.
- [Biodegradable memorials for fish](/guides/biodegradable-memorials) Plantable urns, water-soluble urns and what the eco labels really promise.
- [Short rituals after an aquarium fish dies](/guides/aquarium-loss-ritual) Ten-minute goodbyes for families, classrooms and people living alone.
Each guide opens with a short answer, then goes into the detail. None of them assumes you'll choose cremation. For many small fish, a burial or a simple ritual is the kinder and more sensible choice, and we say so.
All guides
In-depth guides to the decisions families face, written in plain English.
Small goodbye rituals when an aquarium fish dies
Ten-minute goodbye rituals for a tank fish, for families, kids, solo keepers, offices and classrooms, plus tank care after and when to get another fish.
Biodegradable urns and plantable memorials for fish
Water-soluble urns, bio urns and plantable memorials for koi and tank fish: prices, why ashes never go in your own pond, and whether a small fish needs an urn.
How much ash does a fish leave after cremation?
A big koi can leave a few ounces of ash; a betta may leave nothing you can collect. What to expect by size, what a symbolic return is, and what to ask first.
Pond-side markers: remembering a koi where it lived
Mark the spot by the pond after a koi dies: stone types and prices, where to set it so nothing leaches into the water, engraving, lilies and frost-proof bases.
Why fish are different
Why do fish keepers need their own aftercare advice?
Fish are kept in enormous numbers, yet almost every pet aftercare page is written with a Labrador in mind. In the US, the American Pet Products Association counts about 10 million[1] households with freshwater fish and another 2 million[2] keep saltwater species. Most of those homes have more than one: 77%[3] of US fish owners keep two or more.
The practical questions are different too. A dog owner rarely worries that the body will harm the animals left behind, but a dead fish in warm water can foul a tank within hours. Dog owners don't ask whether a crematory will find anything to return. And nobody suggests flushing a cat.
Ponds matter as much as tanks. In the UK, 11% of households keep an outdoor pond with fish and 13% keep an indoor tank[4], and across Europe, FEDIAF's 2025 facts and figures count about 17.6 million[5] home aquariums. Koi in those ponds can live 30-40 years[6], which is why the loss of a pond fish can feel like losing part of the garden's history.
The honest question
Will there be any ashes to bring home from your fish?
Cremated remains are mostly bone, and pets typically leave 3-5% of body weight[7]. Fish sit at the bottom of that range, and often below it, because their bodies are mostly water and their skeletons are delicate. A 12 lb koi can leave a few ounces. A neon tetra weighs well under a gram to begin with.
That doesn't make cremation wrong for a small fish, but it changes what you're paying for. Some families want the certainty that their fish was treated with care, even if nothing separate comes back. Others would rather put the money toward a stone or a plant. Our ash yield guide explains how to ask a provider what they expect to return before you pay.
Free tool
Ashes weight estimator
See roughly how much ash to expect back, by species and body weight.
If you're still weighing up cremation against burial or communal options, the services page sets out every choice with typical prices, and private vs communal cremation for fish covers the difference in detail.
Marking the place
How can you remember a pond fish without harming the pond?
Many koi keepers want the memorial right beside the water, where they fed the fish every morning. That's a lovely instinct, with one catch: ashes are strongly alkaline and shouldn't wash into the pond. Cremated remains test at a pH of ~11.7[8], well above what koi tolerate, so markers and plantings belong a little way back from the edge.
The pond-side markers guide covers stones, engraving, frost and herons. If you'd rather choose something that returns to the earth, the biodegradable memorials guide compares plantable and water-soluble urns. In the US, one retailer sells engraved garden stones from $38.95[9], so a lasting marker doesn't have to cost much. Our estimate across three sellers puts the median starting price at about $39[10].
Which memorial feels right for a fish?
Tap an answer to vote and see how others answered. Anonymous.
At the tank
What does a goodbye look like for an aquarium fish?
For a goldfish on a child's dresser or a betta on an office desk, the goodbye is often more important than the aftercare. A few minutes of attention, a name said out loud and a small drawing can mean more than any urn. The aquarium ritual guide has short ideas for families, classrooms and people who live alone.
Children are often at the center of these losses. In the RSPCA's large UK survey, 93.4%[11] of parents wanted better guidance on helping children through a pet's death. Our guide keeps the advice simple: tell the truth in plain words, let children help, and don't rush to replace the fish overnight.
A fish that lived in a glass box on the kitchen counter was still part of every breakfast. Its goodbye deserves a few quiet minutes.
How we write
How are these fish guides researched and checked?
Every figure with a footnote links to a source you can check, listed on our research page. Fish-specific studies of cremation are scarce, so where the only data comes from dogs and cats we say so and treat it as an upper guide. We'd rather tell you "nobody has measured this" than invent a precise-sounding number.
We're an independent guide and request service, not a crematory. We don't collect, cremate or bury fish, and we don't sell urns. Our about page explains how requests work and the rules we write by, including no reviews, ratings or invented customer stories.
Shorter reads
Where can you find quicker answers and local help?
The fish aftercare blog answers single questions in a few minutes: what cremation costs, what to ask a provider, how to move a large koi and how to cope with grief after a fish dies. Our grief article is a good place to start if the loss has hit harder than you expected.
For local rules and providers, browse the locations directory. And if you'd like someone to do the searching, send us a few details about your fish and we'll reply by email with options that serve your area.
Reader polls
What would you choose?
Vote anonymously and see how other readers answered. The results are live counts from people who visit this site, so they show real opinions, not a scientific sample.
Which fish are you thinking about right now?
Tap an answer to vote and see how others answered. Anonymous.
Which memorial feels right for a fish?
Tap an answer to vote and see how others answered. Anonymous.
When did you (or will you) decide on aftercare?
Tap an answer to vote and see how others answered. Anonymous.
Free tools to help you plan
Ashes weight estimator
See roughly how much ash to expect back, by species and body weight.
Aftercare options compared
Compare private, communal and water cremation with burial on cost, timing and what comes home.
Memorial budget planner
Add up cremation, urn, keepsakes and a farewell so the total holds no surprises.
Questions people ask
Are these guides only for koi?
No. Koi get a lot of attention because they're large and long-lived, but the guides cover pond goldfish, fancy goldfish, bettas, community tropical fish, cichlids and marine fish too. Where the advice differs by size, we say which fish it applies to, because a 15 lb koi and a 3 gram guppy need very different plans.
Is it worth cremating a small aquarium fish?
It depends on what you want from it. A very small fish may leave nothing that can be separated and returned, so if your goal is an urn at home, burial or a memorial may suit you better. If you simply want your fish handled with care, communal cremation is a respectful, low-cost choice. Ask the provider what they expect to return before paying.
Can I put my fish's ashes in the pond or tank?
It's not a good idea. Cremated remains are highly alkaline and can shift the water chemistry your other fish depend on. Keep ashes in a small urn, a keepsake or a garden spot a sensible distance from the water, and let the pond or tank remember the fish in other ways, such as a new plant.
Do you arrange fish cremation yourselves?
No. We're an independent guide and request service. We explain the options, publish sourced price ranges and, if you send us your details, reply by email with providers and choices that serve your area. The provider you choose handles your fish directly, and nothing is booked until you contact them.
What's the difference between the guides and the blog?
The guides take one wider topic, such as marking a pond fish's place or what a fish leaves after cremation, and cover it thoroughly. Blog articles answer a single focused question, like what to ask a provider or how cremation quotes compare. Both open with the short answer, so you can stop reading as soon as you have what you need.
Keep reading
Sources and our estimates
- [1] About 10 million US households keep freshwater fish. American Pet Products Association (APPA) 2025 National Pet Owners Survey release, 2025.
- [2] About 2 million US households keep saltwater fish. American Pet Products Association (APPA) 2025 National Pet Owners Survey release, 2025.
- [3] 77% of U.S. fish owners keep two or more fish (APPA 2025). American Pet Products Association - From Bigger Tanks to Stronger Bonds: Fish & Reptile Ownership Evolves in 2025, 2025.
- [4] 13% of UK households keep indoor fish and 11% keep outdoor pond fish (2026). UK Pet Food (industry association) - UK Pet Population 2026, 2026.
- [5] Europe has about 17.6 million home aquariums. FEDIAF European Pet Food, Facts & Figures 2025 (2023 data), 2023.
- [6] Nishikigoi (koi) typically live about 30 to 40 years depending on their environment. All Japan Nishikigoi Promotion Association - Ancient koi 'Hanako', 2024.
- [7] Embrace notes cremated remains typically weigh about 3-5% of the pet's original body weight. Embrace Pet Insurance - Bury or Cremate Your Dog? Costs, Pros & Cons, 2025.
- [8] Cremated remains have a very high pH of approximately 11.7, which is toxic to plants without amendment. Larkspur Conservation — Giving Cremated Remains a New Life Through Science, 2024.
- [9] Memorials.com's engraved pet garden stones start at $38.95, cultured-stone markers at $87.95 and flat granite markers at $157.95. Memorials.com – Pet Memorial Stones, 2026.
- [10] Engraved pet garden stones start at about $39 at the median of three US sellers. Our estimate: median of starting prices [$38 Adirondack, $38.95 Memorials.com, $89.99 Comfort Co.]. How we calculate.
- [11] 93.4% of parents in the RSPCA survey wanted better guidance on helping children through pet loss. RSPCA — Pet Loss Survey Results, 2026.
Get fish aftercare options near you
Tell us what you need and where you are. We'll reply by email with clear options and prices so you can decide in your own time.