Fluval Flex 32.5 Small octopus

Jan 18, 2021
I had originally thought to buy am larger aquarium, but decided to start smaller and get some experience with a salt water aquarium before getting an octopus.

I have a Fluval Flex 32.5 US Gal Aquarium. https://fluvalaquatics.com/us/flex-32/

The aquarium has been cycled and has 4 Blue Green Chromis. I will be adding several fish for the grandchildren. The fish will be removed before I get an octopus. I also have a terrarium with several Fiddler crabs in waiting.

All this is in preparation for an octopus. The Fluval Flex 32.5 comes with a built 3-stage, two chamber filter area.

To the built in filter system I have added a felt Filter (sheet) as a new first stage.

The first built-in filter is a large foam mechanical filter. This is followed by a carbon filter. The last filter before the protein skimmer is a Fluval Biomax filter.

The protein skimmer is a Fluval Sea PS 1 Protein Skimmer

At present the 50 watt Fluval Heater keeps the tank temperature at 22° C

The circulation pump is 214 US Gal/h.

I have been using the ATC refractometer as well as the Hanna HI98319 tester to measure salinity

I also use a “Saltwater Master Test Kit” to measure the Ammonia, Nitrite, Nitrate and ph values.

Temperature: 22° C, Salinity: 28, Ammonia:0.1, Nitrite:0, Nitrate:0, ph: 7.8

I have a 40 gallon RODI system to provide water for water changes.

To prevent the octopus from escaping I have added reinforcement around the filter area and filled any gaps with “Square Large Foam”.
The attached pictures show the aquarium and a top view showing the Skimmer.


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Staff member
May 30, 2000
nice setup, and thanks for sharing all the specs! Traditionally 32g is considered too small for an octopus, but I do understand it depends on species so there are exceptions... The problem with this is that it's very hard to get a confirmed species from an LFS -- they'll often attempt to identify it, but almost just as often get it wrong.


Larger Pacific Striped Octopus
Staff member
Jul 13, 2008
Looks like a great set up for dwarf species! As Tonmo points out, it’s hard to get a good ID from suppliers, but as long as you stick with dwarf species you should be fine. You’re off to a great start. I love my smaller Fluval EVO tanks, so I’m really going to enjoy following your progress with this one.