Clownfish died out of nowhere

[Jjonesiii100]

Okay, so I am still kind of new to this, but I have had two false percula clowns in my tank for a year now. I have a 120 semi-reef (not too many corals), Here is my tank.

120 (5 Foot Tank)

2 Paired Percula Clowns (the clown that just died was the much larger, aggressive one)
3 Red Firefish
1 Flame Angel
1 Pink Anthias
1 Manadarin Goby
1 Yellow Tank
1 Powdered Blue

None of my fish are aggressive toward each other except the yellow tang is beating up on the powdered blue since he was just introduced.

I also have 2 anemones (a bubble tip which the clowns have been hosting for 2 weeks and a long tentacle).

I will note that the long tentacle looks slightly shriveled up this morning other than that everything looks fine.

The female clown that died was just found laying on the sand bed. Ammonia, Nitrite, and Nitrate have been 0, 0, and always <10 respectively.

All the other fish are completely fine. The female clown was found on the side of the tank she normally doesn't venture to. There is nothing I noticed on her before she died, she was 100% healthy and was acting completely normal last night.

This is extremely saddening to me as she was my first fish and the first one I have lost. My clowns just started hosting their anemone together, and they were displaying breeding behavior. (Twitching with other clown, cleaning a tile I put in the tank with the clowns). I can't help but feel like I have done something wrong.

Does anyone have any idea what could have happened?

Thank you for all of your help.

 

[Jisko]

how old is the tank?

did the clown have any marks on it when you found it dead?

 

[Jjonesiii100]

A little over a year. My girlfriend took it out as I am away. She didn't see anything but she is going to double check before we flush her. She took a picture of the male and said she saw this spot.

 

[Jisko]

hhhmm I wonder if any of the more experience people know... @saltyfilmfolks #reefsquad

 

[davocean]

Many possibilities, but my first thought is maybe it got tail spiked by one of the tangs, yellow would be my first suspect, and I'd expect aggression issues w/ those two tangs in a 120g

 

[mikenestle]

Was the powder blue quarantined?

 

[Jjonesiii100]

I made the mistake of not quarantining the powdered blue. He was introduced about 2 weeks ago. The yellow has been aggressive on the powdered blue. If he doesn't stop I'm going to have to get rid of the powdered blue.

 

[Jjonesiii100]

The side of the tank where she was found dead is where the mandarin goby spends 95% of his time. I find it odd she went over there because she almost never goes in that half. I was told mandarins have toxins that can kill fish if they feel threatened. Is this true, and if so is it possible she died from that?

 

[mikenestle]

I would keep an eye on your other fish, scratching swimming in poweheads ect. Powdered Blue Tangs are notorious for ich. Clownfish may not show symptoms and just die.

 

[davocean]

It is possible the PBT brought something into tank.
As for the mandarin, 2 things, it should not be confined or regular to one area/side of tank, but rather comb the entire tank seeking pods all day, and second, no it would not harm the clown.

The fact your clown was on the other side means little, flow alone could have pushed it there, it spent energy staying in one place, dead it will go wherever