• Looking to buy a cephalopod? Check out Tomh's Cephs Forum, and this post in particular shares important info about our policies as it relates to responsible ceph-keeping.

Pardon my ignorance .......


Mar 2, 2007
How do I know whether my bimaculoides is a boy or a girl .... I just got (it) and want to give (it) an appropriate name ....

Also .... when is a good time to introduce toys into the aquarium?

One more thing .... I have a UV sterilizer on the tank .... should I run it continuously or occasionally ... and if occasionally, how often?

How old is your bimac? I believe the only way to tell is to look for a modified 3rd right arm in males, but it doesn't develop until sexual maturity... most people aren't sure of their octo's sex until it shows it's a she by laying eggs, since the hectocotylus (the modified arm in males) is pretty subtle in most octopuses. A few species have other sexual characteristics (enlarged suckers on some arms in GPOs, dramatically shorter arm in wunderpus, sexual displays in cuttlefish) but most cephs are quite hard to sex, particularly since you can't get them to stick out their arms and hold still.

The other questions are interesting, but I don't really know, so hopefully the experienced ceph-keepers can answer about toys and UV... I know Carol has had a lot of success getting her octos to play with toys, in particular.
Like Monty said, the hectocotylus will not appear until your animal reaches sexual maturity. That is pretty much the only way to tell for most species.

As for toys, I don't have much experience with that either, but I don't think it would hurt to put one in once your octo gets used to it's environment. Just see how he reacts to it.

I can't remember if a UV sterilizer is not recommended because it isn't needed for an octo or for some other reason that could hurt them. I do know they aren't part of a regular octo setup though.
I did remember one important thing about toys: make sure that there is no copper, nor copper alloys in the toys you're considering. It's probably best to avoid any toy that has metal parts entirely.

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