To fish or not to fish... AKA is my "pico" too small?

[eag]

I've done some research here, and also read a bunch of previous threads/questions on this site and others, so I know that to a (large?) degree, the answer to this question is based on opinion... Yet I still struggle with it, so I'm soliciting help from you all.

I am thinking about getting a fish for my mixed reef tank. It's technically a 7.4 gallon tank, but the actual water volume is closer to ~5 gallons. Build thread linked on my badge if it's useful.

What is unclear to me is this: in a bare bottom mixed reef tank with only 5 gallons water volume, exactly what kind of fish, if any, is appropriate? I'm not interested in having any sad fish around... Fish that like to swim around a lot, or fish that would really prefer a substrate, are probably out of the question? Anyone here keep a happy fish under similar circumstances?

 

[Tamberav]

I have two tiny species of blennies and a goby in a 5g pico. None of them are swimmers except when food hits the water.

I am talking about blennies, like pictus, two spot blenny, barnacle blennies, or gobies like eviota. So things that max out at an inch-ish and are more of perching types.

 

[ichthyogeek]

You could do some fun stuff with Gobiodon okinawae (a single specimen). I've heard that neon dottybacks are also recommended for pico aquariums, but your mileage may vary...

Endler's livebearers could work in a small tank like that. Colorful, and if you have carnivorous corals, at least some number of the colony will go into feeding the corals.

Eviota and Trimma gobies are also going to be a safe bet.

 

[afboundguy]

Fish that aren't active swimmers would work. If you want to stay pico sized in fish as well you could get a clown goby. Super small fish that could fit right in with your pico tank.

If you go with another goby be aware that a lot rely on sand sifting to eat microfauna as their main source of food so choose appropriately.

 

[Katrina71]

A tailspot would be fun to watch in there.

 

[SMSREEF]

Agree with above green clown goby or tailspot blenny. Cool little fish with big personalities.

 

[najer]

Different but similar to the tail spot, my twin spot in my Evo 13.5 G, check out the asterina as a size comparison!

 

[Zionas]

I’d probably look into 1 Gobiodon and another very small species of Goby at most.

 

[eag]

Thank you so much everyone for the thoughtful replies! I've done a bunch of googling based on the feedback here, and am leaning towards a tailspot. I've read accounts of other folks who have kept them successfully in smaller tanks than mine, including bare bottom tanks. As far as the other blenny options - they all look good, but I like the look of the tailspot the best . I do see though that they get a tad bigger than some of the other suggestions here - any concerns?

Clown goby sounded great at first, but after some research and a hint from a friend I see that they are known to nip at corals, particularly SPS like acros... I do keep SPS and like them very much, so I think the clown goby is out for that reason?

 

[ichthyogeek]

I've got concerns about the tailspot. Those do get relatively large and hefty compared to other nano fish. I can see one working in a 10, but maybe not a 5.

As for the clown goby, that's nesting behavior. They'll nip a small area out to lay their eggs, but it's not significant, and most likely would happen with some SPS but not all SPS. If you're keeping Acros, then I'd pass on one unless you have a mature multibranching colony.

I'm not sure about gobies sifting sand for microfauna. That's mostly a Valenciennea thing, and those get way too big for a 5 gallon. Trimma, Eviota, and Elacatinus are for the most part zooplanktivores.

 

[eag]

I've got concerns about the tailspot. Those do get relatively large and hefty compared to other nano fish. I can see one working in a 10, but maybe not a 5.

Hmm ok... I had read about people keeping these in tanks as small as 3 gallons, but I see that the maximum size is 2.5 inches and when taking a ruler to the tank it does seem a little big... The only problem is that the max size of even the twin spot (helpfully pictured above by @najer) is listed in some places as 2 inches... so that is kind of confusing.

As for the clown goby, that's nesting behavior. They'll nip a small area out to lay their eggs, but it's not significant, and most likely would happen with some SPS but not all SPS. If you're keeping Acros, then I'd pass on one unless you have a mature multibranching colony.

I do have some acros, and they're not very large now nor do I doubt that they could ever get too large given size constraints (I'll likely have to trim them back once they grow larger). Part of getting a fish is because I'm trying to replace a trio of sexy shrimp that have taken to feasting on my SPS. Here is a recent picture of the tank to give you an idea of what we're working with. The cyphastrea in the bottom left is 3 inches across left to right

I guess I should explore the goby options more closely as well

 

[SMSREEF]

I never had a problem with mine nipping at coral. They do perch on them though (never bothered them too much). I think they look really cool perched on corals.
This was mine years ago in my nano.

And this is a new guy in my larger cube

 

[lotekfish]

Masked gobies are somewhat common, stay small, and are free swimming. Not as much personality as a blenny but I like the one I had. I also really like neon gobies, but they aren't swimmers so much.