Clownfish - Gasping, Listless, Twitching

[Yosef]

A bit of background: I've had a 70 gallon FOWLR setup for about 9 months (my first saltie) with 70 pounds of live rock, assorted inverts, and two clownfish (added about 6 months ago).

Recently, I've noticed that both clownfish have been acting listless, and one in particular has been sitting at the surface and goes into twitching spasms. They've been exhibiting very minor symptoms for a month or two, but I never really noticed until they worsened in the past week. I've also noticed that both fish have darkened in the past month, but that's probably just maturation(?)

From doing some searches, it seems like the twitching could just be a submission ritual (it's the smaller clown that's afflicted), but it doesn't seem like submission displays would be this extreme, plus there's gasping at the surface. Maybe parasites?

Water parameters:
pH: 8.3
ammonia: 0
nitrites: 0
nitrates: <5 ppm
salinity: 1.023
temperature: 77 Fahrenheit (varies by plus/minus one degree - yes, I really need to fix that)

Any help would be appreciated!!!

 

[Bifferwine]

Your parameters look perfect.

Do you have enough powerheads in your tank?

 

[BL1]

Welcome to the site!

The twitching does sound like submission. What kind of water movement do you have in the tank?

What do you need to fix about the temperature? It sounds like everything's ok there, to me.

 

[little_fish]

Hello and Welcome!

Biff and BL1 have you covered!

 

[Yosef]

I could probably use some more water movement - I have two powerheads and two filter outputs. I tried adding an airstone yesterday to see if oxygen was the problem, but the one clownfish is still gasping at the surface.

As far as temperature, I thought that much temperature variation was too much?

 

[BL1]

Well, you want your temperature to be as stable as possible but +/- 1 degree during the day isn't bad at all. What are the GPH on your two powerheads?

 

[Yosef]

Ok. The powerheads add up to 550 GPH.

 

[little_fish]

Ya, i suspect you dont have enough flow to keep the water oxygenated enough. Until you can get more powerheads i would aim one directly at the surface to get good surface agitation to help the gas exchange.

You want your total tank volume to be turned over at least 20 times per hour, if you have SPS corals you want it to be higher than that, LPS like a little less flow.

 

[Yosef]

But if adding an airstone didn't fix the problem, why would adding powerheads? Also, if it's just an oxygenation problem, why would one clownfish be gasping at the surface, but another be fine? I'm sure you're probably right, but being a newbie, I'm curious.

 

[little_fish]

Just running bubble through one small part of the tank is not going to impart much oxygen to the water and remove the CO2, and adding the airstone is actually going to cause you more problems because its going to mess with your pH. I would just remove it.

And fish are funny like that, i cant give you an exact answer for why one is reacting so dramatically. But maybe the other one is just a bit tougher or he hasnt figured out there there is more oxygen closer to the surface.

The reason why powerheads are far more effective at promoting gas exchange is because they are far better at moving the water that is more saturated with with CO2 from your fish and corals respirating to the surface of the tank where the CO2 can diffuse out and O2 diffuse in. Then the powerheads will draw the water with the high O2 saturation down to where the corals and fish can utilize the oxygen. Cycle repeats. Wastes are carried away, nutrients carried in.

With out that extra water movement, the diffusion of gases happens much more slowly because the water at the surface the concentration of oxygen and CO2 are much closer to atmospheric conditions so the driving force behind the diffusion is much smaller.

 

[Yosef]

Ah, that makes sense - thanks. I pulled out the airstone, and will be heading to the store for some powerheads once the parental unit gets a chance to. I guess I'm going for about 1000 GPH more movement.