What is this tiny creature please?

[Mrty]

New too marine aquaria. Cycled my tank. All stats good. Assorted fish including clean up. Fine for 3 months. Then red algae ( I put it down to over feeding, so reduced feeding and increased water changes. Stabilised. Month later, one fish died. (Don't know how old fish is when you buy it, no obvious damage or marks so shrugged shoulders and carried on). Then fish died one after another. All fish died. Soft corals are fine.
No obvious marks on damage on any of the dead fish.
All levels are fine except nitrates which is high even after a water change. That's what puzzles me, if I do a 25% water change surely the nitrate level must do? I've even checked the water from the aquatic centre - zero nitrates.
On to the main question. What is in the picture? It's about one eighth of an inch long ( I don't do metric, I'm an old git). It appeared shortly after some snails appeared , not purchased, I assume hitch hikers in with a coral. Would it also have hitch hikers in or is it possible to get critters from the frozen food cubes?

Any help would be appreciated.

 

[Saltyreef]

Hi @Mrty
This looks like a live Mysis Shrimp.
If so, its quite harmless and would provide plenty of beneficial nutrients for your tank as it may be able to reproduce and aid in feeding your tank

 

[Rick's Reviews]

Loads of information and loadsa guys ready to offer advice@mrty
You say you lost alot of fish, alot of people can help you with creating a beautiful aquarium and avoid those unnecessary loss..

 

[Mrty]

Hi @Mrty
This looks like a live Mysis Shrimp.
If so, its quite harmless and would provide plenty of beneficial nutrients for your tank as it may be able to reproduce and aid in feeding your tank

Many thanks. I was concerned that it caused the fish deaths. So probably the high Nitrate levels them.
Could this Mysis shrimp have come in frozen Mysis shrimp food?

 

[WheatToast]

Could this Mysis shrimp have come in frozen Mysis shrimp food?

Frozen mysis should be long dead. The pictured individual probably hitchhiked on live rock, macroalgae, or frags.

 

[davidcalgary29]

macroalgae

Chaeto, in particular. Those things provide the perfect habitat for all sorts of arthropods.

 

[monkeyCmonkeyDo]

The red algae is most likely actually cyanobacteria. A basic micro organism capable of multiplying and reproducing given the right conditions.
When u talk about your fish dieing 1 by 1 until they all died. It is a trickle effect.
Ammonia and nitrate build up.
Your tank might have cycled but wasn't able to handle all the bio load u gave it immediately. Your better off stocking marine aquariums slowly over time than one big livestock dump.
Sorry for your losses and hope u bounce back from this!
Reef on
Don't be afraid to ask questions either.
Only dumb questions are those un asked.
D

 

[Mrty]

Thanks all. I have had snails hitch hike, and I know some small creatures can survive being frozen, which is why I asked. I'm going to start populating again once I've got the nitrates down. Will start slowly. Here's a pic before the big death. Grandkids probably scared them to death by putting their toys looking in.