Newer 20gal long tank, fish keep dying

[casscoker]

Hi everyone, I’m newer to saltwater aquariums and I’m having trouble with my 20gal long aquarium. I started this aquarium about 3 months ago with dry rock and live sand. Made sure it was cycled 100% before adding anything else into it. I now have various corals, a peppermint shrimp, rock flower anemone, and a mangrove that are all thriving in the tank. Originally I had a purple dotty back in the tank as well. He died several weeks ago. Couldn’t figure out why! I checked my water chems and nothing was out of the ordinary and none of the corals or the anemone showed any signs of stress. I did a water change, waited a week and then tried adding two small clownfish to the tank. They just died yesterday and the second one today. I found the first one under a rock (I’m assuming it’s from the shrimp or hermits pulling it in) and today the larger clown was wedged between a rock and a muscle shell. I purchased the clowns 5 days ago. I always acclimate my fish before putting them in the tank and they didn’t seem overly stressed from the short transport. Please help! I have listed my water chems below, let me know if you see anything out of the ordinary. I would love to have a successful reef tank with fish and coral!

pH is 8.5, nitrate is <5, nitrite 0.1, ammonia is 0.3, salinity 1.025, temp 78

Thank you for the help and suggestions I really appreciate it!

 

[casscoker]

Here are some other photos of the tank and the items in it. I also forgot to mention I have several snails and a couple hermit crabs in the tank for a clean up crew. I haven’t ever had a bad algae or diatom bloom in the tank either so that’s not the problem! I also always top off with RO out of the glass jar on top of the filter so salinity is never super high or low.

 

[Sebastiancrab]

Sounds like you might have the velvet parasite in your tank if your fish died quickly. It might also be ammonia. It needs to be zero! What test kit are you using? Don't use API as it will always give a slight reading. Hanna or Salifert are recommended. Without pictures taken in white light while your fish are alive a fish medic can only venture a guess. It's either a parasite or your ammonia most likely. I suggest you take your tank fallow and then start slow with one fish in a separate quarantine tank. Follow Jay Hemdal's quarantine procedures below in a 10 gallon tank. You cannot use copper in your DT if you are going to have coral. That is the best way to ensure success with your fish.

Current Quarantine Protocol

2023 Quarantine Procedures Jay Hemdal David Scarborough Protozoans (Cryptocaryon/ich, Amyloodinium/velvet) and Metazoan trematodes/flukes are by far the most common parasites found on newly acquired fish. A carefully managed quarantine process can effectively eliminate these parasites before...

www.reef2reef.com

 

[casscoker]

Sounds like you might have the velvet parasite in your tank if your fish died quickly. It might also be ammonia. It needs to be zero! What test kit are you using? Don't use API as it will always give a slight reading. Hanna or Salifert are recommended. Without pictures taken in white light while your fish are alive a fish medic can only venture a guess. It's either a parasite or your ammonia most likely. I suggest you take your tank fallow and then start slow with one fish in a separate quarantine tank. Follow Jay Hemdal's quarantine procedures below in a 10 gallon tank. You cannot use copper in your DT if you are going to have coral. That is the best way to ensure success with your fish.

Current Quarantine Protocol

2023 Quarantine Procedures Jay Hemdal David Scarborough Protozoans (Cryptocaryon/ich, Amyloodinium/velvet) and Metazoan trematodes/flukes are by far the most common parasites found on newly acquired fish. A carefully managed quarantine process can effectively eliminate these parasites before...

www.reef2reef.com

I am using the fluval ammonia test with the dropper chemicals. Here's a video of the fish in bright light from yesterday.