Lethargic clown

[clownpond]

Help all advice is appreciated.
I have a 40 gallon overflow style tank filtration with a protein skimmer. Temp set to 79*F 3 carbon sponges and a biomedia bag. Water parameters are 8.0 pH 0.25ppm ammonia 0 nitrite 0 nitrate salinity is 32 or 1.024 specific gravity.
I’ve had a pair of clowns (black longfin and a moody storm clown) for 4 years now. My black longfin over night lost 70% of a pectoral fin and died this morning. I did a 25% water change added prime. My moody storm is now rapidly heavy breathing and lethargic on the sand and not eating. I did a freshwater dip for 4 minutes at 85*F added 4 scoops of metroplex to the tank turned off the uv light and removed the carbon sponges. Moody is looking rough and I don’t want to lose him and I’m thinking I might have fin rot or parasites in tank.

Tank mates: 3 clownfish (tangerine, gladiator, white storm) 3 electric scallops, 1 hermit crab, 8 snails, 2 sea urchins (1 tuxedo, 1 black long spine), a nasu tang (3 years recently downsized from a 70gal antigravity tank in December and need to rehome him), and a yellowtail damsel (1 year also planning to rehome).

I decided to convert to an all clown tank and added the gladiator about 2 months ago and did well, I added the tangerine to give him a mate and the longfin and storm did not receive it well and I went back to add a second gladiator and white storm to distribute the attention. My 2nd gladiator hid under the live rock so it wasn’t uncommon to not see him but after 2 days of not seeing him at feeding time I searched and he was completely gone with no signs of him in the tank. I thought maybe the black urchin got to him somehow as it also likes to hang out back there but now I’m really stressed I’ll lose all my fish. Please help. Remaining clowns are all doing well atm and get along as they all came from the same tank from the fish store but added different times. Do I have fin rot, parasites, or bad invertebrates?

 

[Mr. Mojo Rising]

I think you are seeing stress and aggression. The general rule is 2 clowns per tank, the third generally gets killed off. Nasu tang should be in a 180 gallon tank!! The damsel in that mix doesn't help, damsels are evil. This is not a good mix of fish for a 40 gallon, it will undoubtedly lead to death or disease, sorry to be straightforward. I understand they were together for some time, but sometimes it takes a while for aggression to show, I've had fish fine together for more than 3 years and then start fighting and I had to rehome the fish. Fish's attitudes change as they grow.

 

[clownpond]

I think you are seeing stress and aggression. The general rule is 2 clowns per tank, the third generally gets killed off. Nasu tang should be in a 180 gallon tank!! The damsel in that mix doesn't help, damsels are evil. This is not a good mix of fish for a 40 gallon, it will undoubtedly lead to death or disease, sorry to be straightforward. I understand they were together for some time, but sometimes it takes a while for aggression to show, I've had fish fine together for more than 3 years and then start fighting and I had to rehome the fish. Fish's attitudes change as they grow.

I’m rehoming the damsel and nasu tang.

 

[clownpond]

Help all advice is appreciated.
I have a 40 gallon overflow style tank filtration with a protein skimmer. Temp set to 79*F 3 carbon sponges and a biomedia bag. Water parameters are 8.0 pH 0.25ppm ammonia 0 nitrite 0 nitrate salinity is 32 or 1.024 specific gravity.
I’ve had a pair of clowns (black longfin and a moody storm clown) for 4 years now. My black longfin over night lost 70% of a pectoral fin and died this morning. I did a 25% water change added prime. My moody storm is now rapidly heavy breathing and lethargic on the sand and not eating. I did a freshwater dip for 4 minutes at 85*F added 4 scoops of metroplex to the tank turned off the uv light and removed the carbon sponges. Moody is looking rough and I don’t want to lose him and I’m thinking I might have fin rot or parasites in tank.

Tank mates: 3 clownfish (tangerine, gladiator, white storm) 3 electric scallops, 1 hermit crab, 8 snails, 2 sea urchins (1 tuxedo, 1 black long spine), a nasu tang (3 years recently downsized from a 70gal antigravity tank in December and need to rehome him), and a yellowtail damsel (1 year also planning to rehome).

I decided to convert to an all clown tank and added the gladiator about 2 months ago and did well, I added the tangerine to give him a mate and the longfin and storm did not receive it well and I went back to add a second gladiator and white storm to distribute the attention. My 2nd gladiator hid under the live rock so it wasn’t uncommon to not see him but after 2 days of not seeing him at feeding time I searched and he was completely gone with no signs of him in the tank. I thought maybe the black urchin got to him somehow as it also likes to hang out back there but now I’m really stressed I’ll lose all my fish. Please help. Remaining clowns are all doing well atm and get along as they all came from the same tank from the fish store but added different times. Do I have fin rot, parasites, or bad invertebrates?

Update: freshwater dip and metroplex seemed to keep him from worsening and he’s attempting to get off the sand and swim a bit, but still experiencing the same symptoms so I went to the fish store and they said it’s brooklynella and to treat for 14 days. Picked up some focus for the metroplex and got some rally pro! Hoping this helps in time. Was recommended to keep the kessil light on low and continue running the protein skimmer but to remove the collection cup.