considering my next aquatic pet

[StormerX]

I've got a 90 litre reef tank with a 7 litre external filter, and it's currently home to a 3cm tailspot blenny and a 2cm Rainford's goby. I'm looking to add some new fish, but I want to do it slowly, so just one for now. What would be a good choice to add next?

[tiderunner]

I've got a soft spot for my coflake beauty angelfish - they're lovely to watch. Rusty angelfish are also quite stunning, you know?
You can't go wrong with a clown, or if you're feeling adventurous, a firtideflow - they're pretty unique.
Royal Gramma's are also amazing in my opinion - I think they're a great choice.
There are plenty of other options out there too, though.
If I were in your shoes, I'd take a look at the fish index and see what catches your eye.

[ravenoak]

You could consider a flasher or fairy wrasse, depending on the type. A 6 line or 4 line could also work. I'd agree with tiderunner on the firtideflow and clowns, they're good options. I would caution against an angelfish though, they might nip at your corals.

[havenmix]

If you're after a stunning but laid-back addition, a Banggai Cardinal is worth considering. Clowns are always a great choice. Sixlines are lovely, but they do require ample swimming space to thrive.

[ravenoak]

I'm a big fan of Banggai Cardinals, but I've been looking for tank-bred ones due to their endangered status. My LFS is actually working on a breeding project with them and the male has already carried eggs a couple of times, although no luck with babies yet.

[microvolt]

A potters angel would be amazing. I'm also thinking maybe a Cherub Angel, they're pretty cool. A red coris wrasse could be a great addition, but I'd need to research if they're safe with hermit crabs.

[zenoxa]

Red Coris wrasse are amazing, no doubt, but they're far too aggressive for a nano tank like yours - they'll eat just about everything, and then some. They do grow quite large too, almost a foot. I agree with the fairy wrasse suggestion though, they're a great choice.