Sudden, mysterious fish deaths

ADreef · 02/28/2006, 12:00 PM

Posting this to see if anyone has any ideas about this. I have a 29 gallon tank with live rock, a few corals (zenia, zoos, muchrooms, yellow polyps), the usual snails and hermits, and until yesterday, a bi-color blenny and a Kole tang.

The tank has been running for several years, and the fish had been in there for most of that time. The blenny has been looking pretty skinny for many many months, but has been acting healthy (eating well, etc.). The tang had always been active and a healthy eater. All of a sudden (like overnight), the tang was dead and the blenny was staying in his hole and breathing heavily. That was yesterday. Today the blenny was dead.

I pretty lazy about testing the water, but I do fairly regular water changes. Everything else in the tank looks OK - no change at all in the appearance of any of the corals, snails, or crabs. The only recent change I have made is that I added a peppermint shrimp and an emerald crab (a small one) about 9 days ago.

Is it possible for a crab or shrimp to carry something bad from the LFS into my tank - something that would all-of-a-sudden kill two healthy fish after a week? Maybe the skinny blenny was really in a weakened state that allowed him to catch something that he then transfered to the tang (except the tang was healthier and died first).

Those were the only two fish in the tank. I am tempted to buy a cheap damsel or something to put in there and see if it catches something.

As far as a hidden predator goes...I have wondered about that since I can't ever seem to keep peppermint shrimp (Aiptasia control) in there for very long. However, if there is something like that in there, it would have had to have been in there for a long time now - like two years or so. Other than the occasional shrimp, nothing else has mysteriously disappeared and no fish have ever shown any wounds from being attacked.

If anyone has any ideas, suggestions, or related experiences to share I would love to hear them.

Thanks.

reefshadow · 02/28/2006, 12:38 PM

First of all,

To Reef Central

A kole in a 29 gallon for several years? You are going to get alot of flak for that. Too small by far in my opinion.

It's hard to say what happened without testing, and posting parameters. A few thoughts though- That is a pretty high bioload for a 29... what was the size of the tang? Do you have a skimmer? Heavy water movement? Could have been a amm/nitrite spike coupled with a reduction in o2. There is very little room for play in a heavily loaded 29.

Yes, you can introduce disease pathogens with ANY addition. Inverts, corals, rock, etc...

More info on params and equipment would be helpful.

Please don't put another tang in there!

ADreef · 02/28/2006, 12:53 PM

Yeah, I know, it is a small tank for a tang. I didn't know that when I bought it and the LFS didn't tell me it was a bad idea at the time. The tang was small - about 2" or a little less. It didn't really grow in size while I had him, but he was always active and ate well. Never showed any obvious signs of stress.

I have been planning on upgrading to a 90-gallon, which is one reason why I kept the tang. But with a new kid in the house, it has been hard to find the time to build a stand for the new tank, figure out the plumbing, etc., etc., etc.

I haven't had time to test the tank parameters. I found the dead tang late last night and the blenny this morning before I went to work. I will try to do some tests tonight.

mickyfin · 02/28/2006, 02:07 PM

Do try.

You need to take a mopre active role in your tank, friend!

Perhaps since you seem to have little time, this hobby is not a good fit for your lifestyle? Not trying to be harsh, but do consider this before restocking your tank!

ADreef · 03/01/2006, 10:50 AM

Ran some water tests last night:

Ammonia, nitrite, nitrate, phosphate - all negligible

As luck would have it, my pH test kit had run out. I forgot to buy more during my last trip to the LFS. However, I did measure the alkalinity and it was only a little over 5dKH. Maybe this is low enough to allow the pH to drop? If pH is an issue, wouldn't at least some of the corals exhibit some stress?
I'll pick up another pH kit this evening.

02/28/2006, 12:00 PM	#1
ADreef Registered Member Join Date: Jan 2006 Location: San Diego, CA Posts: 41	Sudden, mysterious fish deaths Posting this to see if anyone has any ideas about this. I have a 29 gallon tank with live rock, a few corals (zenia, zoos, muchrooms, yellow polyps), the usual snails and hermits, and until yesterday, a bi-color blenny and a Kole tang. The tank has been running for several years, and the fish had been in there for most of that time. The blenny has been looking pretty skinny for many many months, but has been acting healthy (eating well, etc.). The tang had always been active and a healthy eater. All of a sudden (like overnight), the tang was dead and the blenny was staying in his hole and breathing heavily. That was yesterday. Today the blenny was dead. I pretty lazy about testing the water, but I do fairly regular water changes. Everything else in the tank looks OK - no change at all in the appearance of any of the corals, snails, or crabs. The only recent change I have made is that I added a peppermint shrimp and an emerald crab (a small one) about 9 days ago. Is it possible for a crab or shrimp to carry something bad from the LFS into my tank - something that would all-of-a-sudden kill two healthy fish after a week? Maybe the skinny blenny was really in a weakened state that allowed him to catch something that he then transfered to the tang (except the tang was healthier and died first). Those were the only two fish in the tank. I am tempted to buy a cheap damsel or something to put in there and see if it catches something. As far as a hidden predator goes...I have wondered about that since I can't ever seem to keep peppermint shrimp (Aiptasia control) in there for very long. However, if there is something like that in there, it would have had to have been in there for a long time now - like two years or so. Other than the occasional shrimp, nothing else has mysteriously disappeared and no fish have ever shown any wounds from being attacked. If anyone has any ideas, suggestions, or related experiences to share I would love to hear them. Thanks.

02/28/2006, 12:38 PM	#2
reefshadow Registered Member Join Date: Jan 2003 Location: Central Washington Posts: 1,786	First of all, *To Reef Central* A kole in a 29 gallon for several years? You are going to get alot of flak for that. Too small by far in my opinion. It's hard to say what happened without testing, and posting parameters. A few thoughts though- That is a pretty high bioload for a 29... what was the size of the tang? Do you have a skimmer? Heavy water movement? Could have been a amm/nitrite spike coupled with a reduction in o2. There is very little room for play in a heavily loaded 29. Yes, you can introduce disease pathogens with ANY addition. Inverts, corals, rock, etc... More info on params and equipment would be helpful. Please don't put another tang in there! __________________ All Your Coral Are Belong To Us Current Tank Info: 30 Deep Blue shallow mixed rimless, MP10, Ecoxotic LED's, SCA 301 skimmer.

02/28/2006, 02:07 PM	#4
mickyfin Registered Member Join Date: Jul 2004 Location: Ottawa, Canada Posts: 320	Do try. You need to take a mopre active role in your tank, friend! Perhaps since you seem to have little time, this hobby is not a good fit for your lifestyle? Not trying to be harsh, but do consider this before restocking your tank! __________________ "If you're gonna be dumb, ya gotta be tough." Current Tank Info: 120 gal mixed reef

02/28/2006, 12:53 PM	#3
ADreef Registered Member Join Date: Jan 2006 Location: San Diego, CA Posts: 41	Yeah, I know, it is a small tank for a tang. I didn't know that when I bought it and the LFS didn't tell me it was a bad idea at the time. The tang was small - about 2" or a little less. It didn't really grow in size while I had him, but he was always active and ate well. Never showed any obvious signs of stress. I have been planning on upgrading to a 90-gallon, which is one reason why I kept the tang. But with a new kid in the house, it has been hard to find the time to build a stand for the new tank, figure out the plumbing, etc., etc., etc. I haven't had time to test the tank parameters. I found the dead tang late last night and the blenny this morning before I went to work. I will try to do some tests tonight.

03/01/2006, 10:50 AM	#5
ADreef Registered Member Join Date: Jan 2006 Location: San Diego, CA Posts: 41	Ran some water tests last night: Ammonia, nitrite, nitrate, phosphate - all negligible As luck would have it, my pH test kit had run out. I forgot to buy more during my last trip to the LFS. However, I did measure the alkalinity and it was only a little over 5dKH. Maybe this is low enough to allow the pH to drop? If pH is an issue, wouldn't at least some of the corals exhibit some stress? I'll pick up another pH kit this evening.