my fish died

[Ralph823]

If it was the water, the crab more than likely would have died too. I mean it is possible that it could've been the crab but they usually grab one thing at a time and then scurry back into the rocks to devour it. I've never seen one go on a killing spree.

serial killer crab . Idk I truly am stumped.

 

[exnisstech]

instant ocean is 1/2 a cup for every US gallon

You are correct. My old memory doesn't work so well sometime.
Interesting that it mixes that high for you. I have been using it for years and always mix 16 cups of salt to yield 27 gallons at 1.025

 

[Fishy888]

I keep my water at - 1.024 sometimes slightly higher 1.026 or as low as 1.023 but I like to stay in the 1.024-1.026 range, instant ocean is 1/2 a cup for every US gallon and that will bring salinity way above where I keep it about 1.028ish, so I either dose just under 1/2 a cup of instant ocean or I'll add a cup of fresh water at a time until I get the desired salinity. I then test with a refractometer and keep a hydrometer in the tank at all times stuck to the wall "even tho hydrometers are less accurate it gives me an estimate of my tanks salinity daily. I soak my hydrometer in white vinegar weekly to ensure that it stays clean and reliable.

Actually 1/2 cup per gallon of IO gives a SG of 1.021. I use 2.5 cups per 4 gallons which yields 1.026. 1.021 is brackish.

 

[Dom]

I yeeted him out the window but it wasnt a shrimp it kind of looked like an emerald crab but longer pinchers and a darker shade of green, it was probably an inch and a half to two inches long... I have no idea how I missed it plus I dip my live rocks before I put them in the tanks.

I think hitch-hikers are cool. I'm starting a separate tank just for them.

 

[j.falk]

serial killer crab . Idk I truly am stumped.

 

[Fishy888]

that's where I'm stumped, my only explanation is that dang crab, but everyone one here seems to disagree that the crab was the cause so I guess I'm just waiting until another reasonable explanation comes up, I assume if it was that batch of water something more sensitive in another tank would've died also like my seahorses or my mandarins. which I keep together in a 32 bio cube.

The problem is that crabs aren’t the fastest creatures in the sea. The only way a crab even has a chance at a healthy fish is if the fish is sleeping and there wasn’t a shred of light in there. Since you did a water change there must have been light enough to see by. Now if you caught the crab red handed I would agree with you but consider this. That crab had been living in that rock unattended for however long you’ve had it.

Within the span of a few hours you lose your fish, AND a crab you’d probably never have noticed suddenly appears out of nowhere. I think the same chemistry issue that killed the fish also distressed the crab enough to make it come out too. Usually they like to hide until it’s completely dark.

Your crab sounds like an adult emerald crab. I have a juvenile. It stays hidden. I’ve only seen it once though I know what rock it lives in. I know because I moved some rock around recently and saw it. Emerald crabs are omnivorous but are opportunistic. They’re going for the easy meal.Eating algae and excess fish food is much easier than trying to kill a fish as big as they are.

 

[woodyarmadillo]

Dumb question but I didn’t see it mentioned so figured I’d throw it out. Did you heat the water or make sure it was a reasonable temp before you added?

 

[Ralph823]

Actually 1/2 cup per gallon of IO gives a SG of 1.021. I use 2.5 cups per 4 gallons which yields 1.026. 1.021 is brackish.

my tanks are consistently at 1.024-1.026 are u scraping excess off the top? I don't so we probably end up adding the same amount. if my mixture is too salty I can always add fresh water to the mixture until I get it right, I rather had to add more water than add more salt.

 

[Idech]

Disturbing the sand when you haven’t done it in a long time can cause an ammonia peak and quickly kill fish. Was this perhaps done in your tank ?

 

[Ralph823]

The problem is that crabs aren’t the fastest creatures in the sea. The only way a crab even has a chance at a healthy fish is if the fish is sleeping and there wasn’t a shred of light in there. Since you did a water change there must have been light enough to see by. Now if you caught the crab red handed I would agree with you but consider this. That crab had been living in that rock unattended for however long you’ve had it.

Within the span of a few hours you lose your fish, AND a crab you’d probably never have noticed suddenly appears out of nowhere. I think the same chemistry issue that killed the fish also distressed the crab enough to make it come out too. Usually they like to hide until it’s completely dark.

Your crab sounds like an adult emerald crab. I have a juvenile. It stays hidden. I’ve only seen it once though I know what rock it lives in. I know because I moved some rock around recently and saw it. Emerald crabs are omnivorous but are opportunistic. They’re going for the easy meal.Eating algae and excess fish food is much easier than trying to kill a fish as big as they are.

I Turn all lights off to change water, just something my dad taught me growing up, he says if the fish are asleep the commotion will stress them out less, idk how true that is but its how I've done it ever since, I did catch the crab trying to eat my still living clown ( fish is fine just missing some of the tail fin) the next day.

 

[TokenReefer]

Any chance you startled them enough that they swam hard into something as you were changing the water with the lights off?

Sorry for your losses. Interesting mystery here. Following..

 

[Fishy888]

my tanks are consistently at 1.024-1.026 are u scraping excess off the top? I don't so we probably end up adding the same amount. if my mixture is too salty I can always add fresh water to the mixture until I get it right, I rather had to add more water than add more salt.

Do you use regular IO or do you use reef crystals?

 

[Fishy888]

I Turn all lights off to change water, just something my dad taught me growing up, he says if the fish are asleep the commotion will stress them out less, idk how true that is but its how I've done it ever since, I did catch the crab trying to eat my still living clown ( fish is fine just missing some of the tail fin) the next day.

If the fish was truly fine the crab wouldn’t have gone for it. Hopefully it’ll get better but something is way off.

 

[Ralph823]

Dumb question but I didn’t see it mentioned so figured I’d throw it out. Did you heat the water or make sure it was a reasonable temp before you added?

I don't heat the water just because its only 10% if I were to do a 20-30% water change then I would, also I use a thin syphon to add the water back to the tank to not stir up the substrate and stress the fish, the syphon I use takes about 5-10 minutes to drain out 7.25 gallons depending on how I set the valve, so I cant imagine adding water to the tank at that rate would shock their temp. I keep my tank at 78 degrees and keep my salt mixture aerating the garage for about 45 minutes, the garage stays at around 75 degrees, its also where I keep the jugs of fresh water so a 3 degree difference in temp for 10% added to the aquarium slowly shouldn't be a problem.

 

[Ralph823]

Any chance you startled them enough that they swam hard into something as you were changing the water with the lights off?

Sorry for your losses. Interesting mystery here. Following..

i mean i guess its possible

 

[Ralph823]

Disturbing the sand when you haven’t done it in a long time can cause an ammonia peak and quickly kill fish. Was this perhaps done in your tank ?

I syphon a small part of the sand and with each water change i move to another spot to not stir up the sand for that exact reason, im sure its possible but im not sure it was the cause.

 

[Ralph823]

he looked similar but not as dark

 

[Ralph823]

Do you use regular IO or do you use reef crystals?

depends on the tank, anything with corals or anemones i use reef crystals, fish only i use regular

 

[Ralph823]

If the fish was truly fine the crab wouldn’t have gone for it. Hopefully it’ll get better but something is way off.

I just got home from work and am going to take my water to another LFS and get a second opinion and see what could've gone wrong.

 

[slipknot23]

And find out what test kits they use