Word of caution: Archerfish and sponge filters don't seem to mix.

[Gannon]

Not too long ago I began running a sponge filter sized for 40 gallons in my 125 gallon aquarium instead of the powerhead that blows a little water forward and some at the surface to get some oxygenation. I wanted to have something energy efficient to run in an emergency power outage scenario that would do oxygenation and some filtration for low energy so my whole fish room would be relatively okay. Once I added it, my clouded archerfish were fairly immediately pale, but got over it and I figured they were just stressed about it because it was new and it wouldn't be a big deal going forward, to be safe I turned down the sponge filter a lot, it was connected to a very large air pump, but I adjusted air flow to be much slower than even a sponge filter of that size would need. I figured I could slowly work up to it, since I've noticed my archers at least are easily spooked and a bit sensitive to new things. While nothing major happened, I noticed an increase in small to moderate fin tears and a couple missing scales in the next couple weeks or so before I finally decided it wasn't worth it and turned it off. What do you know, once things are back to the normal powerhead they are all fine healed up, and have absolutely no new fin tears or missing scales. It definitely seems to me that this correlation could be causation, as there were no other changes made to the tank. I also used to run a bubbler in that tank for some surface film and remember more fin tears around that time too. It definitely does happen without bubblers or sponge filters but not often. I imagine it has to be at night or something where the bubbles or the upward current spooks them? Or maybe it's something else. 

Has anyone else ran into an issue like this with archerfish or other animals? I may try putting the sponge filter in a different spot one day but for now it just doesn't seem to be worth the stress and headache. Also, I'd like to hear your thoughts on this story, I thought it was an interesting thing to share as I haven't heard of anything like this before, maybe I'm mistaken and its fairly common. 

[Odd Duck]

No experience related to archers but I’ve got an adult Jack Dempsey pair that fairly regularly startle for no apparent reason semi-regularly after lights out. I think it’s most likely the Plecos startling them, but who knows?  They’re the most chicken big fish I’ve known and they don’t need any excuse to get startled during the night. 🤦🏻‍♀️ 🤷🏻‍♀️ 

[Gannon]

On 12/12/2022 at 9:44 PM, Odd Duck said:

No experience related to archers but I’ve got an adult Jack Dempsey pair that fairly regularly startle for no apparent reason semi-regularly after lights out. I think it’s most likely the Plecos startling them, but who knows?  They’re the most chicken big fish I’ve known and they don’t need any excuse to get startled during the night. 🤦🏻‍♀️ 🤷🏻‍♀️ 

my archers actually used to be terrified of my green phantom pleco and would dart around. Seems to no longer be an issue. 

[nabokovfan87]

On 12/12/2022 at 7:44 PM, Odd Duck said:

No experience related to archers but I’ve got an adult Jack Dempsey pair that fairly regularly startle for no apparent reason semi-regularly after lights out.

Noise or vibration?

@Gannon Can you show us the flow in a video or something?  Maybe that'll help out.

[Gannon]

I don't think I can post videos on here! otherwise I would, but it was a very light flow.

[Flumpweesel]

At least they are happy now, certainly seems odd I wonder if the bubbles made them more active hunting wise, mimicked their prey some odd way that makes no sense how we see the world.

Or high O2 triggering breeding behaviour and aggression that goes with that.

[Gannon]

On 12/13/2022 at 4:15 PM, Flumpweesel said:

At least they are happy now, certainly seems odd I wonder if the bubbles made them more active hunting wise, mimicked their prey some odd way that makes no sense how we see the world.

Or high O2 triggering breeding behaviour and aggression that goes with that.

I doubt it could be breeding. As far as I'm aware they haven't been bred in captivity but I could be mistaken. My best guess is just that it simply spooks them as even people approaching the tank at night can really startle them. The other plausible possibility is that the bubble erruptions seem to confuse them for prey items hitting the water, but i highly doubt this.