What could be killing all my fish

I have had a salt water fish tank for years but something kept killing all the fish. we had the water checked and everything was fine. well we moved and decided to start all over so we put in new sand and rock and let the tank cycle for 3 months. then we added the cleaner crew - turbo snails, and a few other types of snails. left them for about 6 weeks before adding fish. then we added a sand sifting cucumber, a yellow tail blue damsel, a royal dotty back, a clown fish, a snowflake eel, an orange star fish and a pencil urchin. I checked the watter all the time and it was fine. we went to bed one night and got up the next morning and the eel was gone - we thought maybe he had gotten out but nope. then one by one the fish came up missing in the following order.royal dotty back, blue damsel, clown fish, all the cleaner crew, the cucumber, the star fish. all that is left is the urchin. the water through all of this has never tested off. we also had a lot of green and purple algea (the good kind of green and purple) now all we have is brown algea - and lots of it. but the water still test fine. I cannot figure what would kill everything in the tank especailly since we had this happen before and decided to start over hoping that would cure the issue.

 

Tank size, filter system, skimmer, what kind of sand, rock? Maintenance schedule? How do you check your water - test strip or test kits? What are the parameters? Did you add all fish at the same time? What are the sizes of the fish? Did you find dead fish and remove it? How long between each death?

 

I have a 29 gallon bio cube. Live rock live sand. maintanence as needed. i use a test kit (not strips). The fish were all babies. we never found any of them dead in the tank they were just there one day gone the next. it was about 24 hours between each death. all fish were added at the same time. they were fine for about a month before they started disapperaing - this time.

 

mantis shrimp killing them maybe?

 

First, I am sorry for your losses.
Second, If you didn't pull out the eel and just couldn't find him, I would say it was him, in the Library, with the knife, with Colonel Mustard!

My friend had the same thing happen. It was the eel even though they target fed him.

 

Sounds alot like many mantis stories I've heard.

"Tank was fine for X months then Y just disappeared in Z days."

 

or someone is breaking in the house at night and stealing your fish!

I had a 3' long snowflake.. went on 1 week vacation back in 2000, came home couldnt find the eel for 2 days.. thought he was stolen or something.. started to smell something nasty, well the eel got out and was on the floor behind the stand.. it was nasty. hard as a rock.. love eels but they are nitrate makers, and fish killers too.. so dont get any more eels and you'll be alright..

 

I eel was def gone - we even took the rock and searched it looking for him in the rock thinking it was him eating the fish.

 

how do we know if it is mantis and how do we get rid of them? its odd that both times I set the tank up (from new everything) that the same thing happened.

 

That is very odd, it's even odder you never found any bodies. While the CUC will make relatively quick work of a dead animal, I would think you would be able to find the remains of an eel.