Red Ruby Behavior

[xenia2]

I just got a red ruby dragonet for my 3.5 gallons tank, it is the only fish and eating frozen. The problem I have is that its becomes agitated when the light off (wants to jump out of the tank).

Isvthis their typical behavior when the light goes off?

[MondoBongo]

3.5 gallon tank? that's not a typo?

i can't recommend strongly enough that you return that fish. that is not anything even resembling an acceptable habitat for a dragonet, and will not allow you long term success.

[xenia2]

What is the recommend tank size for dragonet?

[MondoBongo]

live aquaria lists 30 gallons as the recommended minimum size for Synchiropus stellatus, and i tend to think that is a bit small. attainable with the right setup, but small, and that would be for one tiny dragonet with no competition. they grow fast.

http://www.liveaquaria.com/product/prod_display.cfm?c=15+1635+91&pcatid=91

realistically 40 - 55g for the "scooters" and 70+ for the "mandarins" is my general guidelines.

the primary issue being how they feed, and what they feed on. these guys are grazers on benthic copepods. they eat all day long, striking every couple seconds at nearly invisible prey. they also have digestive systems that have more in common with syngnathids, seahorses and pipefish, than they do with other bony fish. the eat small, and eat often. with a limited ability to store or "get full" from large meals.

because of this, they need large areas to roam over, rocks and sand, where they can hunt. you would be shocked at just efficient a predator these fish are. coincidentally this is also why it is recommended that you wait at least 6, but preferably 12, months before adding a dragonet to an established tank. to give the copepod populations time to grow and stabilize.

without seeing the behavior myself it is hard to say definitively, but neither of mine do that (i keep a Synchiropus splendidus and Synchiropus ocellatus). they will occasionally go up the glass, but usually in search of food. the S. ocellatus seems more interested in doing this than the S. splendidus (the S. ocellatus is more like your S. stellatus).

there is a good chance that the very confined space is freaking the fish out.

[xenia2]

More like freaking out in the dark lol. Fish acting fine when the light on.