The short version
- Typical range: £20 – £150 — see the full fish tank value guide
- What decides your price: condition, and how well you evidence it in photographs
- Cost to sell here: nothing, at any price
- Category: Pet Supplies
Before you photograph it
Ten minutes here is worth more than anything else you will do. Buyers are deciding between your listing and someone else’s, and preparation is what visibly separates the two.
- Fill it and leave it standing for several hours on a flat surface, then check every seam for weeping.
- Inspect the internal silicone for lifting, discolouration or gaps at the corners.
- Clean off limescale tide marks with an aquarium-safe method, and check the glass for scratches by feel as well as sight.
The photographs that sell a fish tank
Four photographs do almost all the work. Shoot in daylight, near a window, with the item against something plain — and do not use the flash, which flattens texture and hides exactly what buyers are trying to see.
- The empty tank straight on, on a plain surface, in good light
- The internal corner seams close up, showing the silicone
- The base and edges, showing chips or scratches
- The lid, hood or brace bars if included, plus any damage
Photograph the flaws too. It feels counterproductive, but a listing that shows the worst of an item gets fewer questions, fewer withdrawn offers and fewer arguments at handover. Buyers who can see the damage stop imagining something worse.
Writing the title and description
Volume and dimensions: “120L Glass Fish Tank, 100x40x40cm, Empty”. Say empty or bare in the title so buyers do not arrive expecting equipment — if yours includes filter and heater, it is a setup and belongs in the aquarium guide instead.
Then state these in the description, because a buyer who has to ask is a buyer who might not bother:
- Volume in litres and exact external dimensions
- Glass thickness if known, and whether it is braced or rimless
- Age of the tank and whether the seals have been water tested
- Whether a lid, hood, light bar or stand is included
What buyers will actually ask
You will receive the same three messages about a fish tank. Answering them in the listing itself removes the back-and-forth, and answering them well when they do arrive is what turns an enquiry into a sale.
Fill it, wait, and report what happened. An untested old tank is worth far less than a tested one because the buyer is carrying all the risk.
Give your honest estimate. Silicone has a working life, and buyers of tanks over about a decade old often plan to reseal as a precaution.
Run a fingernail over any mark. Scratches you can feel are in the glass and permanent; surface film cleans off. Photograph anything significant.
Pricing it so it actually sells
Start from the honest condition grade rather than the price you hope for. WishThrift listings use five grades — New with Tags, Like New, Good, Fair and For Parts — and what each grade means is worth reading before you choose, because grading up is the most expensive mistake sellers make. It does not raise the price; it produces a buyer who arrives expecting something else.
The fish tank value guide prices all five grades for this item. Pick your grade, take the figure, and if you sit between two grades price toward the lower one. Items priced honestly sell faster than items priced hopefully, and on a free platform there is no fee eating the difference anyway.
What you keep, compared
On a £85 sale — roughly the middle of the range for a fish tank — here is what the commission-charging platforms would take, and what you would keep on each:
| Where you sell it | Fee | You keep |
|---|---|---|
| WishThrift | £0 | £85 |
| Poshmark | −£17 | £68 |
| eBay | −£12 | £73 |
| Mercari | −£8 | £77 |
| Etsy | −£6 | £79 |
Seller-side rates verified 26 Jul 2026 — Poshmark: 20% commission on sales of $15 and above; eBay: 13.6% final value fee, plus a per-order fee; Mercari: flat 10% selling fee; Etsy: 6.5% transaction fee, plus a listing fee and payment processing. Percentages are applied to the sterling figure above; the fixed per-order and processing charges those platforms add are quoted in their own currency and are not included here, so the real deductions are slightly larger. Full breakdown: marketplace selling fees compared.
Timing and getting it to the buyer
Steady year round with an autumn and January lift. Standard sizes sell within a couple of weeks; very large tanks are slower because few buyers have the floor for them.
Collection, empty and dry. Carry it flat and supported underneath, never by the rim or on edge, and never with substrate or water inside — that is how tanks crack in transit.
WishThrift does not process payments or arrange delivery — you and the buyer agree both directly — so confirm payment has cleared before the item leaves your hands, and keep the conversation on the site so there is a record of what was agreed.
Ready to list it? It takes about two minutes, costs nothing, and there is no commission when it sells — create a free account or see how selling works.
Frequently asked questions
What is a used fish tank worth?
Typically £20 to £150 for the tank alone, driven by volume and seal condition. See the fish tank value guide for the condition bands.
Can a leaking tank be resealed?
Yes — stripping and replacing the internal silicone is a standard job that plenty of fishkeepers do themselves. Describe it honestly as needing a reseal and it still sells, just for less.
What is the difference between this and an aquarium listing?
A fish tank is the glass box; an aquarium is a running setup with filter, heater, lighting and often a cabinet. List whichever you actually have, because buyers search for them differently and price them very differently.
See also: what a used fish tank is worth · browse live pet supplies listings · condition grades explained.