Cardinal fish dead unexpectedly

[PokeFish]

I have had three striped cardinal fish for several months, but today I found one of them dying on the sand bed. I had to euthanize cuz he wasn’t gonna make it.

Any ideas as to why he died?
Params and fish in pics below

Only changes I’ve been doing is dosing the tank with alk because of an alk dip.
One of the cardinals also ate a stometella snail, not sure if it choked or something

Tank is several months old and these fish were one of the first inhabitants

 

[eliaslikesfish]

nitrates? phosphates? Are the others showing any signs of illness as well?

 

[PokeFish]

nitrates? phosphates? Are the others showing any signs of illness as well?

Nitrates are 0-5 ppm
Phosphates are around 0.5

Ill test again, but I've stopped because they have been stable for so long

My other fish are fine, except for my tang which suffers occasionally from ich. With that being said, ich has been in my tank since the beginning when my tang introduced it, and has never affected or even been seen on other fish besides my tang!

The cardinal fish also had no white spots (ich) on it when it died. But I'm not too familiar with the parasite... would it disappear once the fish dies?

 

[eliaslikesfish]

Nitrates are 0-5 ppm
Phosphates are around 0.5

Ill test again, but I've stopped because they have been stable for so long

My other fish are fine, except for my tang which suffers occasionally from ich. With that being said, ich has been in my tank since the beginning when my tang introduced it, and has never affected or even been seen on other fish besides my tang!

The cardinal fish also had no white spots (ich) on it when it died. But I'm not too familiar with the parasite... would it disappear once the fish dies?

Hmmmm, how long ago did your tang originally get ich and what treatment did you give? Just because there are no white spots doesn’t mean ich isn’t still present in your water if you haven’t treated it.

 

[Uncle99]

Ick does not disappear when a fish dies, or when all fish die.
Ick dies when there are no fish to feed on for 60-70 days at normal running temps.

 

[Sharkbait19]

Any split fins? Was it staying off from the group at all? It’s possible the other two ganged up on this one to kill it.

What kind of tang? Some show mucus cones that look like ich, but aren’t.

 

[PokeFish]

Hmmmm, how long ago did your tang originally get ich and what treatment did you give? Just because there are no white spots doesn’t mean ich isn’t still present in your water if you haven’t treated it.

About 4 months ago… but Yeah I’m sure ich is still there since my tang gets all pale and itchy bout once a month. It’s just that it hasn’t affected any of my other fish

 

[PokeFish]

Any split fins? Was it staying off from the group at all? It’s possible the other two ganged up on this one to kill it.

What kind of tang? Some show mucus cones that look like ich, but aren’t.

It’s a white tail bristle tooth.

It was the smaller one of the three so it’s possible. I’ll upload a side picture

 

[Sharkbait19]

It’s a white tail bristle tooth.

It was the smaller one of the three so it’s possible. I’ll upload a side picture

The cones are more common on the acanthurus tangs to my knowledge, so quite likely ich on the bristletooth.

As for the cardinal, how long was the anal fin split? Were any inverts getting to it before you euthanized?

 

[PokeFish]

The cones are more common on the acanthurus tangs to my knowledge, so quite likely ich on the bristletooth.

As for the cardinal, how long was the anal fin split? Were any inverts getting to it before you euthanized?

I’m not sure… but I think it may be recent. Is that a sign of bullying?

I have some crabs in the tank but I don’t think they could’ve got to him since he would kind of drift all dead at the bottom but then swim real fast across the tank over and over again

 

[PokeFish]

The cones are more common on the acanthurus tangs to my knowledge, so quite likely ich on the bristletooth.

As for the cardinal, how long was the anal fin split? Were any inverts getting to it before you euthanized?

Come to think of it, I’ve missed a couple feed days. Maybe that could’ve triggered some aggression

 

[Sharkbait19]

I’m not sure… but I think it may be recent. Is that a sign of bullying?

I have some crabs in the tank but I don’t think they could’ve got to him since he would kind of drift all dead at the bottom but then swim real fast across the tank over and over again

Most often split fins are a sign of aggression. With a fish known to be aggressive with conspecifics, I wouldn’t be surprised if the others were the culprits.
Usually the fish needs to already by dead for crabs to get to it.

Come to think of it, I’ve missed a couple feed days. Maybe that could’ve triggered some aggression

Getting hungry can definitely trigger aggression (just like with people). It depends on how much you missed though. A feeding here and there isn’t going to be as bad.
It also could just be coincidence. Often it’s just like a switch is turned and one fish decides they don’t like another anymore.

 

[PokeFish]

Most often split fins are a sign of aggression. With a fish known to be aggressive with conspecifics, I wouldn’t be surprised if the others were the culprits.
Usually the fish needs to already by dead for crabs to get to it.

Getting hungry can definitely trigger aggression (just like with people). It depends on how much you missed though. A feeding here and there isn’t going to be as bad.
It also could just be coincidence. Often it’s just like a switch is turned and one fish decides they don’t like another anymore.

Yes there has always been aggression, some slight chasing here and there, but I didn't observe it to be to the point where one would get killed.