Sand sifting star - keep or not?

Oldsalt · Apr 12, 2019

Hello folks

This has been playing on my mind for a while now. I have a sand sifter star that I believe is upsetting my sand bed. Everywhere he vacates leaves a 5 sided blackish star that seems to grow until I vacuum above it. He's now hiding under a place where I can't easily find him. Although my tank is 350 gallons, I doubt he's getting what he needs nutrition wise plus removing beneficial bacterium, hence these unsightly black blooms.
Should I get him out? My LFS doesn't want him back and I have to wonder if he knows why. I hate killing any living being but if this star is starving, he's suffering slowly. The photo is him after only a week. These black star shaped spots started recently - 5 months after putting him in.

Reefer40b · Apr 12, 2019

I highly doubt the black is from the starfish. How deep is your sandbed? And in a 350 gal tank he has plenty to eat and will not destroy your sand bed. I have kept mine in a 180 for a long while and there is still plenty of life in my sand bed, I probably would not keep one if I had a smaller tank though.

Oldsalt · Apr 12, 2019

Reefer40b said:
I highly doubt the black is from the starfish. How deep is your sandbed? And in a 350 gal tank he has plenty to eat and will not destroy your sand bed. I have kept mine in a 180 for a long while and there is still plenty of life in my sand bed, I probably would not keep one if I had a smaller tank though.

My sand bed is 1.5 oh front tapering up to to 2 inches in the rear.

He's moving around.. I have a feeling that the black marks with his shape are diatoms. The tank is coming up on 1 year old. I had diatom outbreak until 3 months ago.. It's probably going to take a while to get all under control.. Also I started with lousy lights.. Now I upgraded to reef system using real time sunrise to sunset full 4 channel control. Making a huge difference to the diatom brown (can look black if it gets thick). Tomorrow is husbandry day and I'm vacuuming just the tom's out and changing 250 litres (~20% ).

I leave the star in and see what happens. Other folks say that they slowly starve to death even in huge tanks..

Reefer40b · Apr 12, 2019

Oldsalt said:
My sand bed is 1.5 oh front tapering up to to 2 inches in the rear.

He's moving around.. I have a feeling that the black marks with his shape are diatoms. The tank is coming up on 1 year old. I had diatom outbreak until 3 months ago.. It's probably going to take a while to get all under control.. Also I started with lousy lights.. Now I upgraded to reef system using real time sunrise to sunset full 4 channel control. Making a huge difference to the diatom brown (can look black if it gets thick). Tomorrow is husbandry day and I'm vacuuming just the tom's out and changing 250 litres (~20% ).

I leave the star in and see what happens. Other folks say that they slowly starve to death even in huge tanks..

My trigger had a sample at one point bit his leg off and has since grown back fully and has grown quite a bit since i have had him 2.5 years now. I would not vacuum your sand just my preference seems like your destroying the bacterial bed more then the starfish.. and taking his food

Oldsalt · Apr 12, 2019

Reefer40b said:
My trigger had a sample at one point bit his leg off and has since grown back fully and has grown quite a bit since i have had him 2.5 years now. I would not vacuum your sand just my preference seems like your destroying the bacterial bed more then the starfish.. and taking his food

I only ever vacuumed it once. I hesitate to do it at all to be honest. But how else do I skim off the diatoms without risking the good stuff?? When I vacuumed it 6 months ago, I only let the tube barely touch the diatoms. I don't stick the tube in for 2 reasons - 1) I could poke the sifting star and kill it and 2) I like the biodiversity of the sand bed and don't want to mess with it. Also, I used a 50 Micron nylon sock on the other end of the syphon and put it into the sump. It caught all the slimy diatoms and fine surface sand. I rinsed it in sump water and put it back in.
Some folks vacuum like mad and others never. I'm on the fence wondering about pros and cons... There was poll about how we clean up the bottom not long ago and it seemed fairly divided.. It can be a quandary.

Reefer40b · Apr 12, 2019

If its diatoms they will be gone soon enough, you said your tank is a year old... seems odd you have diatoms. You sure your not fighting dinos or brown cyano?

Oldsalt · Apr 12, 2019

Reefer40b said:
If its diatoms they will be gone soon enough, you said your tank is a year old... seems odd you have diatoms. You sure your not fighting dinos or brown cyano?

The tank will be a year old in about 3 months. It was first filled with Indian Ocean water in mid July 2018. It took 6 weeks to cycle. I'm pretty sure it's diatoms. Certainly not cyano. l'll google dino so I can see what it looks like.
I'll also take a photo tomorrow and post it here. Maybe someone can identity it. It's almost 0230 here in Perth.

Oldsalt · Apr 12, 2019

Well...I was going to go to sleep but I decided to look into this black stuff. It is bubbling with lights on. Cyano seems likely. Lights are new and very powerful. Having them set to high and too long in certain spectrums could easily contribute. I read a part of a huge thread here about both cyano and dinos. I'll be reading then taking immediate action tomorrow morning. This stuff has to go!.

Mariette · Apr 12, 2019

If you’re worried about it starving to death, try spot feeding it

Oldsalt · Apr 12, 2019

Ok 9am lights are ramping up and the areas of black faded. They are not everywhere. Only where the star has been and gone recently. Why dark spots the exact outline of the star? This has to be something to do with the starfish itself.
You can't simply spot feed sand sifting stars. They only feed on bacterium in the sand. I read an awful lot this morning and the consensus is that the same sifting starfish shouldn't be in our tanks. They slowly starve to death. It can take months to a few years.
I'm taking it out. He's going back to the LFS. If he says no, I'll leave it on the counter and walk out. This particular guy just gave him to me. He didn't want it. He's since made that many recommendations about marine aquariums that were dead wrong. So I rarely shop there anymore. He tried to sell me lights that were designed for fresh water plant growth, saying that they were perfect for coral!! I KNEW he was incorrect and I told him that I would not spend 800 dollars on 4 foot JAD lights with T5 growlux fluorescent tubes for freshwater fish tanks when I have a mixed reef 6 foot tank! Then he tried to sell me a dozen dominoes saying that they were cheap and easy and totally non aggressive to other fish (What??) and loved to be in a school. I can go on about the Moray eel he said was a "puddycat" and that he'd be great for me or the protein skimmer designed for a tank size of 500 litres when I specifically told him mine was 1500 litres. That's when I decided it was time to go elsewhere.