Mysterious Linkia Starfish Death

[cdness]

As of recent times, I had three linkia starfish in the 125G reef tank. They have been thriving for the longest time with the oldest being in my tank for over 3 years. Within the last two weeks, all three of the linkia starfish have died and I have no idea why. My wife wants to replace them as they technically were hers and my two daughters, but I told her no until we figure out why they died. I do not want to put another one in the tank only for it to wither away and die so let's see if we can get to the bottom of this issue...

Parameters:
Ammonia/Nitrite/Nitrate: 0 (API)
Phosphate: 0.02 (hanna)
Calcium: 440 (Red Sea)
Alkalinity: 7.5 (Red Sea)
Magnesium: 1350 (Red Sea)
Salinity: 1.026 (refractometer & float glass hydrometer)
Temp: 77 - 80 (Apex)
PH: 7.7 - 8 (Apex)

Tank Info:
Tank has been up and running since Dec 2011 but it was an upgrade from the existing 75G which was up for approximately 6 years prior to that. I would estimate the live rock weight to be around 200 pounds wet between the sump and display. It is a VERY mixed reef with pretty much all types of corals from shrooms to acros. Lighting is T-5 and LED. I run a skimmer, bio-pellets, and a little passive GFO and carbon. The fuge has 5 types of algae chaeto, gracilleria, sea lettuce (ulva), Mangroves, and another unknown type of algae.

The only issue I can think of is the failure of my RODI system. My DI resin was shot and the TDS climbed to 14 before I could get new resin into the system. This water was used for water changes and top off.

I have noticed a die off with my sponge population. I am wondering if this is due to the bio-pellets reducing the nutrient levels to extremely low numbers. These were added to try combat the cyano outbreak and reduce phosphates without the use of GFO. I am considering taking them offline and just going back to GFO 100% in a reactor.

Any Linkia experts, please help me determine the cause of their death. If the cause cannot be determined, do you have pointers on where to look for clues or changes to make to the existing system?

 

[Mike J.]

I think that anyone who answers this question is just guessing. So, here's goes my educated guess. Since the Linkia depend on microbial film for most of their food, I have a strong suspicion that the lack thereof caused their demise. Bio-pellets create a condition called assimilatory denitrification. That is, they assimilate with nitrates and phosphates, a lot like plants do. The difference is you have to harvest the plants to remove the nitrates, phosphates and the bio-pellets assimilate the nitrates, phosphates, and even bacteria and bind with proteins and are removed by the skimmer. Since I'm working right now this answer is going to be shorter than I'd like. I suspect that your bio-pellets have removed the microbial film and your starfish have starved to death.

 

[Mike J.]

Sorry for your losses. My wife gets depressed and almost cries when we loose something. I'd hate to lose Twinkles.

 

[cdness]

I think that anyone who answers this question is just guessing. So, here's goes my educated guess. Since the Linkia depend on microbial film for most of their food, I have a strong suspicion that the lack thereof caused their demise. Bio-pellets create a condition called assimilatory denitrification. That is, they assimilate with nitrates and phosphates, a lot like plants do. The difference is you have to harvest the plants to remove the nitrates, phosphates and the bio-pellets assimilate the nitrates, phosphates, and even bacteria and bind with proteins and are removed by the skimmer. Since I'm working right now this answer is going to be shorter than I'd like. I suspect that your bio-pellets have removed the microbial film and your starfish have starved to death.

You know this makes sense. It was supposed to solve one issue, but it ended up causing another issue. I will have a chat with the wife about if she really wants the starfish I will need to find another solution to nutrient levels.

Sorry for your losses. My wife gets depressed and almost cries when we loose something. I'd hate to lose Twinkles.

My daughter doesn't know hers is gone yet. She isn't going to be happy at all.

 

[twelvefive]

Replace it before she realizes, she'll never know!

 

[revhtree Verified Admin]

Honestly my first thought was that they ran out of food. Personally I would only keep one of these stars in a 125g.

Sorry for your loss.

 

[Mike J.]

Honestly my first thought was that they ran out of food. Personally I would only keep one of these stars in a 125g.

Sorry for your loss.

My thought exactly, but I didn't want to point that out in a difficult time like this. and, he did keep them successfully for three years - all tanks are different. Just pushing it a little.

 

[Eienna]

You know this makes sense. It was supposed to solve one issue, but it ended up causing another issue. I will have a chat with the wife about if she really wants the starfish I will need to find another solution to nutrient levels.



My daughter doesn't know hers is gone yet. She isn't going to be happy at all.

I agree. I also agree that only one should be kept.

As far as your daughter being upset...it's a good chance to teach her about being responsible about the animals you keep...or that happen to be unsuited to a particular situation.

In any case, kids usually know when you're lying.