Trying to understand fish and snail death

[forever_learning]

Hi all. Bit of background:

I have a couple of freshwater aquariums and decided to dive into the world of saltwater a while back. I have a 500 liter tank with around 60 liter sump which has been running for 4 months or so. I've been taking things very slow in the hopes the minimise any losses, at least that was the thinking! The cycle took around 5 weeks to complete at which time I added 6 hermit crabs and 6 turbo snails.

I let the tank settle for a week or so before adding 2 clownfish and 3 Banggai cardinalfish which were drip acclimated for around an hour. We lost one of the cardinal fish over the first couple of weeks but didnt think too much of it as there's always risk of loss from what I've seen in freshwater.

From there things were running fine, 0 ammonia and nitrates around 10-15ppm depending on the week. At the weekend though we checked the tank whilst locking the house up for the night, all looking good, and woke the next morning to find all four remaining fish dead, a crab dead and the turbo snails looking a little sluggish. Over the next two days we lost three more turbo snails.

Also in the tank are 2 sand sifting star fish, a cleaner shrimp, and a fire shrimp, all of which seem to be doing ok along with the remaining crabs.

Ammonia on the morning of the extinction was 0.25 and the nitrates slightly above 30. Tested with NT Labs marine kit.

In trying to understand the cause here I'm thinking either the increase in nitrates or perhaps an oxygen starvation, it seems odd to me that all fish wiped out at the same time.

Is there anything I'm missing testing or can be doing to find root cause here? Secondly, what's the next step forward, leave the tank fallow for a while and try again or jump straight back in?

Salinity is 1.025 measured with refractometer
pH 8.2

 

[Mr. Mojo Rising]

Turbo snails eat algae, but I imagine your brand new tank has no algae, they are starving to death. Wait to add the herbivores until you see some algae growth.

All fish dead could be because of disease since you didn't qt. It might be a good idea to go fallow just in case.

But if fish and snails dying it may point to water issue. How do you oxygenate the water? Saltwater doesn't hold oxygen the way freshwater does, so we have to actively oxygenate the water. The best way is with a skimmer, but if no skimmer then you should have a powerhead pointed at the surface to create agitation, agitated in a way that you should see little bubbles enter the water.

Are there rocks in the tank? What kind of filtration do you have? How many powerheads? Tank pictures will help.

 

[forever_learning]

Thanks for the reply! I can get some photos later, there is a fair covering of green on the rockwork. Prior to The Event I did not have a skimmer but added one now, I've also adjusted the powerhead to apply more aggitation to the surface. Other than that, filtration is currently filter socks (regularly cleaned out), some carbon and ceramic rings.

On the QT front I skipped it this time as all 5 were from the same system at the LFS and they have their own QT procedure. I figured as it was the first fish addition then QT could be skipped/done in tank.

Open to any and all comments/feedback/suggestions :)

 

[forever_learning]

Photo of tank :)

 

[W31Olds]

I wouldn't be too concerned about the crab dying or the snails. They sometimes are not good indicators. I agree with Mojo, low 02. Ask your LFS what their QT procedure is? Those fish are probably captive bred so less likely to have parasites unless they run common systems at your LFS.

 

[StartingATank]

Photo of tank :)

I will say it doesn't look like you have a lot of algae, looks like green coralline algae, which I do have, but I have found that the only things that eat it in my tank are turbo snails, which eat a tiny amount of it, don't go all the way down, or and Urchin, which should go all the way down.

 

[Idech]

Photo of tank :)

Add small rocks to the bottom of the existing rocks to create tunnels and caves for the fish. There are no hiding places at the moment and this will cause stress in fish. And stress can bring on disease.

 

[TheNative192]

Photo of tank :)

Sorry for your losses. Whenever multiple things die I think it’s more likely to be a system wide issue as if both snails & fish died it’s less likely to be a disease. Also usually if it is a disease most people would notice something strange looking on their fish.

As such I agree there is a solid chance of the tank not having enough oxygenation. In freshwater we use bubblers or filters to add oxygen and even plants but as you can imagine it is widely different in saltwater. A skimmer should help with this while also managing waste too.

As for other possible problems what do you use to create your saltwater? Do you have an RODI system for top offs and have you calibrated your refractometer recently? Do you have an Auto top off with RODI water? Also did you do a water change prior to their deaths (even up to 5 days prior)? How do you manage temperature? A temperature or salinity swing of one to two degrees can kill the fish or stress them out to the point where they die a couple days later.

I have also seen a lot of people here realize their refractometers lost calibration and they added too much salt which harmed the fish. So definitely check that. Also did the fish have any unusual issues looking when they passed? White patches or bruises etc. If there was a disease it’s been to leave the tank empty to kill it off but that may not be required.

 

[forever_learning]

Thanks for all the repsonses so far! Idech I'll def look into adding some more caves/tunnels/hiding places, was a bit worried about flow on the floor so tried to keep as much off the bottom as possible but will have a play with what I can put together.

TheNative192, great questions! I currently buy saltwater direct from LFS for now which I check with refractometer before adding, will need some serious house rejiggery to make it at home but working on plans here. Refractometer hasnt been calibrated since purchase a couple of months ago when I last did it. How often would you say it requires calibration?

Auto topoff with RODI water, the graph shows consistant additions so nothing out of the ordinary there. Temp graph is also consistent throughout.

Previous water change was a week and a half before the event, I did another large water change post event becuase it felt right to do.

No spots at all, and no weird behaviour from the fish prior. For all 4 to go in the exact same 8 hour window I'm def suspecting oxygen now. Following Mojo's response, I've increased the power of the wave maker and directed it more towards the surface so there's bubbles being visibly pulled into the water column.

As for moving forward, I'll leave it a week or so to bring up the oxygen levels and think about reintroducing a pair of tank bred clownfish (as previous). Good idea or wait some weeks more?

 

[Tcook]

You will also need to feed those stars. There is nothing in that new sandbed for them. Hold off on further cuc for a month or two. As others have pointed out, overnight death of both fish and invertebrates is low O2 or toxin. Toxin unlikely with the other inverts doing well.

 

[W31Olds]

Temp and salinity swings are unlikely to cause your fish to perish overnight, and 2 degrees Fahrenheit should not be a problem. Did you add any bacteria or other supplements? Household chemicals, cleaning supplies, or lotions soaps can cause problems if they find a way onto your tank. O2 is the most likely suspect.

 

[TheNative192]

Thanks for all the repsonses so far! Idech I'll def look into adding some more caves/tunnels/hiding places, was a bit worried about flow on the floor so tried to keep as much off the bottom as possible but will have a play with what I can put together.

TheNative192, great questions! I currently buy saltwater direct from LFS for now which I check with refractometer before adding, will need some serious house rejiggery to make it at home but working on plans here. Refractometer hasnt been calibrated since purchase a couple of months ago when I last did it. How often would you say it requires calibration?

Auto topoff with RODI water, the graph shows consistant additions so nothing out of the ordinary there. Temp graph is also consistent throughout.

Previous water change was a week and a half before the event, I did another large water change post event becuase it felt right to do.

No spots at all, and no weird behaviour from the fish prior. For all 4 to go in the exact same 8 hour window I'm def suspecting oxygen now. Following Mojo's response, I've increased the power of the wave maker and directed it more towards the surface so there's bubbles being visibly pulled into the water column.

As for moving forward, I'll leave it a week or so to bring up the oxygen levels and think about reintroducing a pair of tank bred clownfish (as previous). Good idea or wait some weeks more?

I assume you have a heater to temp acclimate the water for water changes.

For refractometer I always check one a month or before doing water changes. Just take some RODI water or even tap or distilled water and just make sure that it is 0 reading. Temperature can affect the refractometer reading as well. Most kits come with a screwdriver to adjust if it is off. I don’t have to adjust it often maybe every 6 months on average but it seems to randomly change depending on cost of one you purchased and quality

 

[forever_learning]

Ah in that case I do check it :) I check with RODI water and make sure it's bang on zero. Good shout on the bringing water change temp up, could be doing better there.

W31Olds, I try to keep hands out the tank as much as possible and rinse under water if I ever need to go tank diving. As for cleaning products.... what are they ?

 

[W31Olds]

I don't think you check you refractomer's accuracy with RODI Water but don't quote me on that but I do always try and match replacement water with my tank to a one degree F or two and salinity of +/- .001 sg. I don't use a refractometer, just a Hanna Salinity checker that I verify with a Tropic Marin Hydrometer (Gold Standard). Things like bathroom cleaners , hand lotions, etc.

 

[forever_learning]

I was joking about the cleaning products, I'm constantly told by the other half that I've no idea what they are and how to use them :D

 

[zerozero]

Ah in that case I do check it :) I check with RODI water and make sure it's bang on zero. Good shout on the bringing water change temp up, could be doing better there.

Sorry for your losses.
The water temp probably wasn't a factor in your losses but come the end of the week we're going to have the opposite problem. With temperatures expected to hit 30ºC, if you don't have a tank cooler, you'll have you'll need to put ice cubes in freezer bags to cool the tank. We want the chilling effect of the ice cubes without the melting water to lower the salinity.

 

[forever_learning]

Sorry for your losses.
The water temp probably wasn't a factor in your losses but come the end of the week we're going to have the opposite problem. With temperatures expected to hit 30ºC, if you don't have a tank cooler, you'll have you'll need to put ice cubes in freezer bags to cool the tank. We want the chilling effect of the ice cubes without the melting water to lower the salinity.

Thankfully our house is old enough to have very thick stone walls so it stays lovely and cool, even in the silly heat of a few years ago. Great point about having the ice in bags though!