Blue sponge: mass murderer?!

[thebookshark]

Hey y’all,

I have a blue-purple sponge that came as a hitchhiker on some live rock. It was in my former 10G nano RFA/sexy shrimp tank for a year and grew out really nicely all over the rock. Never fed it but it was mostly under an overhang in the rock so if it’s photosynthetic it didn’t need much light.

Fast forward to my current tank which is a 20G; I transferred the sponge rock over. I know you’re not supposed to expose sponges to air but it was unavoidable and since it came in on the rock (which was packed damp but not wet from the LFS) exposed to air I figured it would either be okay or it wouldn’t. It looked a little scraggly but overall seemed fine since the transfer. Somewhat deflated with a flattened and pebbly/textured appearance where before it was smooth.

HOWEVER…. I have had an inordinate amount of fish mortality in this tank. It’s been up and running for about 6 weeks and all corals and shrimp are doing great. I’ve had 5 fish die in that time, 3 under mysterious circumstances with no signs of illness (the other 2: one jumped out, one was bullied to death). I’ve also lost 3 of my RFAs suddenly- they were all fine, then one by one they detached and melted in 24 hrs or less.

In trying to figure out what the heck is happening in this tank, I noticed in the last few days that part of the sponge is turning brownish. I know some sponges release serious toxins when they die- could this be what’s killing my fish and RFAs?! I assumed it would be affecting everything in the tank, not just fish and anemones. As I said, shrimp and corals are all doing great. My female sexy shrimp even have fully developed eggs, so it seems like the water quality must be good? Parameters below and photo of the sponge as of this morning.

Thanks for your help!

Temp: 78
SG: 1.025
pH: 8-8.2
KH: 7.5-8
Ammonia: 0
Nitrate: 0
Phosphate: 0

 

[Timfish]

For starters, I think it's a myth about sponges dying from being exposed to air. The cryptic sponges that come on live rock, as you have observed, tolerate being out of water for long periods of time. The ornamental species we see, in my experience have done as well when exposed to air as the ones I haven't exposed to air.

As sponges are essential recyclers in reef ecosystems they're beneficial to have. If they bother you though, you can reduce them using steel straws with water changes. As they are recycling nutrients, be aware attempting to aggressivly remove a lot at one time could be messing with how nutrients are being cycled in your system. But the only sponges I'll bother removing are ones growing over corals.

You didn't mention if you've QTed your fish. My suspicion, considering how you have corals and crustacions doing fine, is a combination of stress and disease as the main culprite for your fish loss. At this point if it was my system I would keep doing wtaer changes and wait several months to let things mature befor adding anything.


(Here's some videos you might find interesting)

"Coral Reefs in the Microbial Seas " This video compliments Rohwer's book of the same title. Used copies are available on line and it may be free to read on Internet Archive. Both deal with the conflicting roles of the different types of DOC (carbon dosing) in reef ecosystems and how it can alter coral microbiomes. While there is overlap bewteen his book and the video both have information not covered by the other and together give a broader view of the complex relationships found in reef ecosystems and are an excellent starting point to understand the conflicting roles of Dissolved Organic Carbon (DOC, aka "carbon dosing") in reef ecosystems.


Delbeek Molar Ratios


Changing Seas - Mysterious Microbes


Microbial view of Coral Decline


Nitrogen cycling in hte coral holobiont


BActeria and Sponges Jones


Maintenance of Coral Reef Health (refferences at the end)


Optical Feedback Loop in Colorful Coral Bleaching


DNA Sequencing and the Reef Tank Microbiome


Richard Ross What's up with phosphate"