Red spot on my clownfish… cause for concern?


New member
Hi all!

I’m new to the hobby and have my first tank set-up and cycled. I just introduced a pair of Ocellaris clownfish into my tank yesterday, after having picked them up from my LFS. They had been in quarantine there for about 4 weeks and due to my tank being recently cycled and fishless, I popped them straight into the tank.

Whilst acclimating, I spotted a faint red ‘bruise’ on one of the fish, which you’ll see in the pictures here. Is this any cause for concern or likely a superficial thing that should go away with time?

The other clown has eaten, this one however spits out what I’ve offered so far, although I think that’s quite normal considering it still needs to settle into the new tank. It does seem to be enjoying the copepods in the tank though.

Thanks in advance for any advice ☺️


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Premium Member
Welcome to Reef Central! Also, welcome to the hobby. You will find the hobby exciting, educational, but also at times, expensive. Tell me more about your aquarium (e.g., size/gallons, substrate, contents).

This tank-bred fish should be eating wherever it is. Are you sure the fish is eating the tank pods? I'm assuming the tank it came from (your LFS) didn't have an anemone or other coral in it. If I'm wrong, please let me know.

The red spot could be a bruise from handling, but it looks more like it is under the skin. A bruise would more than likely appear on the surface.

It could be a bacterial infection. At this point in time, watch it closely. A video longer than one minute under white light up close to the fish, showing both sides of the fish would be helpful. You can upload the video to YouTube then post the link to it here.

Do you have medications and a hospital tank? Having a well stocked Marine Fish Medicine Cabinet and a hospital tank are usually good things to have on hand.

The worse-case scenario is that this is an early sign of an Uronema marinum (Uronema) infection. This bacteria can kill quickly. However, with proper feeding as you'll find in the Fish Nutrition post marine fish can thrive even in the presence of Uronema.


New member
Thank you for your kind response and warm welcome! :)

Here is some more info about my aquarium:

100 litres (~80 litres of net water, ~8kg of live rock, ~15kg of live sand)
Ammonia 0
Nitrite slightly higher now after adding the fish, at 0,05 (was 0)
Nitrate 20-35
PH 8.2
Salinity 35ppm
Alkalinity 8.5

I did use Red Sea reef mature starter kit to start up and cycle the tank and have been dosing NO3 PO4-X and KH Coralline Gro as per instructions, into the sump.

Tank inhabitants: 2 Ocellaris clownfish, 2 cleaner shrimp, 1 tuxedo urchin, 1 dwarf blue hermit grab, 2 turbo snails

I asked the LFS what they fed the clownfish and they fed mysis and artemia. Both I’ve tried (defrosted in tank water) in small quantities but this particular fish seems to eat then spit out the pieces. It acted more stressed that the other clown when being introduced so perhaps lost it’s appetite due to the new environment/tank stress? It has been pecking at the glass and back panel where many copepods are so looks like it’s been snacking on them but I could be wrong.

There were no other fish, rocks or coral in the LFS tank, just this pair. They did use a net to take it out so could have gotten a little caught during their handling maybe?

I don’t have a hospital tank or medical supplies as of yet so thank you for recommending! I’ll definitely do my research into that.

The tank lights have gone off for the day (timer) but I will take a video and send it through tomorrow :)


Premium Member
lost it’s appetite due to the new environment/tank stress?
Not likely.
dosing NO3 PO4-X and KH Coralline Gro
Not necessary. Kinda marketing push. If you're serious about adding phosphate (PO4) you will need a good testing kit -- the Hanna Ultra Low Range Checker for accuracy. However, for this nano tank, it is probably not worth it.
Nitrate 20-35
Nitrates and Phosphates encourage green algae as well as coralline. These are ingredients to have the least quantity.
just this pair.
Are they just two or really a pair -- Is this the female or male of the pair, or are they about the same size/length?
little caught during their handling maybe?
The tank lights have gone off for the day (timer) but I will take a video and send it through tomorrow
I don’t have a hospital tank
Owning a nano tank, you may not want to have a hospital tank. Your aquarium is stocked with about as much as it will hold.
1 tuxedo urchin
Often better for a 125 liter or large aquarium. Keeping it fed in a new aquarium may be challenging.


New member
Thanks for your response!

Regarding the clowns, they were sold as “a pair” but are both the same size at the moment.

Thanks for the info on the urchin and the Red Sea products I’ve been adding. I did get nori for when there’s less algae in the tank, to feed the urchin. At the moment there is a decent amount of algae - I think from the high nitrates and it being a newly cycled tank - but the urchin does make quick work of cleaning the rock. I did get a Red Sea phosphate test, unfortunately Hanna is a bit pricey but am sure it works much better!

I wasn’t planning on adding anything new inhabitants to the tank except coral at some point, perhaps in a month or two once I get the hang of things.


Premium Member
except coral
Coral in a nano tank can be very attractive. The soft corals are more tolerant of tank water variations and hard corals can be difficult.
Regarding the clowns, they were sold as “a pair” but are both the same size at the moment.
I was just concerned about them getting along. Often the female will 'bully' the male.
I did get nori
Be sure it is air-dried, or sun-dried. You don't want nori that has been roasted/heated dried. You'll learn more from the fish nutrition post.

Good luck! (y)


New member

Here’s the video of the fish, hope this helps! :) It tends to stay on this side of the tank near the powerhead, in the top half of the tank. You can also see it’s buddy make an appearance



Premium Member
Thank you for the video. I think the fish looks to be okay. I hope this fish will move around the tank like its mate.

Glad to hear the fish is eating. Try to get it to eat better foods. Quite often, Clownfish are particular about the size of their food. So although they may want to eat the food, the food may be too large for the fish to eat.


New member

That’s a relief, thank you very much for your input! I’ll keep an eye on it and make sure it doesn’t get worse and hopefully goes away on its own.

I’ll definitely look into the food doc you sent through and see what I can source locally for a good varied diet. Size could’ve been the issue with the mysis I tried … they are quite big chunks compared to the size of the fish.

Thanks again! :)