# Gambierdiscus | Algae ID

Source: https://algaeid.com/identification/gambierdiscus/

[ID guide](https://algaeid.com/identification/) › Dinoflagellates

# *Gambierdiscus* sp.

**Toxic.** *Gambierdiscus* makes ciguatoxins, the cause of ciguatera. One aquarium professional dealing with a suspected outbreak reported feeling nauseated and dizzy near the tank, and so did the tank's owner. Ventilate, and read the [safety notes](https://algaeid.com/treatment/#safety) before you start.

*Gambierdiscus* is closely related to *Ostreopsis* and has the same basic design: a flat disc that looks like a circle from above, instead of an oval. The cells are large, so if you see big round cells even at fairly low magnification, *Gambierdiscus* is worth considering. It has not been seen as often as *Amphidinium* and *Ostreopsis* in aquaria.

**A clue to look for:** the outline is almost, but not quite, a perfect circle. It looks like someone drew a circle and, when they came around to the end, the line did not quite meet up. That small step or mismatch is where the sulcus meets the cingulum. Remember that in these flat cells the cingulum runs around the rim.

*Gambierdiscus*: the same design as *Ostreopsis*, but round.

I do not have a photo of *Gambierdiscus* of my own yet. If you have a confirmed one, I would love to see it. The [small unidentified dino](https://algaeid.com/identification/other-dinos/#the-small-unidentified-dino) can be mistaken for it when you cannot judge the size.

## What to do

Safety comes first. Ventilate, run fresh carbon, and read the [safety notes](https://algaeid.com/treatment/#safety) before you try anything. I do not have enough data on *Gambierdiscus* in aquaria to say what works best, and aquarists report different results. See the [treatment notes](https://algaeid.com/treatment/) for the approaches I lean toward.

If you have a suspected *Gambierdiscus* outbreak, I would be very interested in good pictures and, if you can keep a small sample alive, a sample for further study. Please [get in touch](https://algaeid.com/contact/).