Sexual dimorphism identification of Chelmon rostratus, the Copperband Butterfly,

[dennis romano]

Well, this CBB pair is a no go. Both were doing OK then just stop eating and died. The rest of the fish in the QT was fin. My Mandarin, Silver belly wrasse and Convict tang are doing great. I was not sure why they died other than the fact that they were keep at the LFS for too long in the coppered treated system. I asked the LFS owner to keep them together to make sure they pair up, or at least tolerate each other. I never prophylactically treat any of my fishes and won't make the same mistake again.
I have since got a CBB from Aquarium Design in San Antonio. She is a small one, only about 2 inches. Looking at her, I would see her size is about a 50 cents US coin. Of course, the snout and clear tail does not count in this type of estimate.
She hunts all day, eating well with mysis feeding twice a day. Full stomach and pooping well. She has a bunch of lymphocystis lesions on her tail and both pectoralis fins when I first got her. Since she is in my QT system, the lesions on the tail and R pectoralis fins have resolved while the lesions on the L pectoralis fin is going away. I am officially in the hunt for a male CBB at this time.
Here she is new in my QT with empty stomach

Full stomach

If you look at the forehead of the two original fish, between the eye stripe and the next stripe, their foreheads are thin and not as full as that as your new fish's. They had issues. The new fish is in good shape.

 

[OrionN]

After 16 days the Lymphocystis completely resolved. Beer belly picture today

 

[OrionN]

Well, I got my pair.. I got a Male CBB from Austin Aqua-Dome 2 days ago om 4/12/2024. He is larger that my Female. Maybe .75 inch bigger. He's thin but disease free and when directly into my QT system. I did not try to isolated him becasue by the time I got home, it was 3 AM Saturday. He was in the bag for 12 hrs, and I did not have the energy to set up the isolation chamber. I was going to get up early Sat AM as soon as the light turn on and ready to set up the chamber if needed. It turn out I did not need to do it. They tolerate each other well. He occasionally run at the female but never actively chase her. I tried to pair unsuccessfully before. It was much more aggressive than that. Day 2 together and they already pair up and swim around each other with no problem. This evening, I feed them frozen mysis, he ate a handful of mysis but not anywhere near as aggressive as the Convict tang or the female CBB. I think I will remove the Convict from the QT over the next several days.
Pictures time. I grab a few quick pictures of the pair just now. The first two pictures white light while the last 2 pictures, the light is dimming and shifted to blue, in preparation turning off.
This picture clearly show the difference in profile of the male and female CBB

Several more pictures of the pair.

 

[Salty_Taste]

Guessing this would be a female?

Newest Edition: Hard to tell because it’s 2in

 

[OrionN]

Guessing this would be a female?

Newest Edition: Hard to tell because it’s 2in

Not at all. This CBB is clearly a female to my eye. Straight on profile picture make it easy to sex CBB

 

[Salty_Taste]

Thanks for the confirmation! I hope this pair does well! What do you typically feed?

 

[OrionN]

I am as happy as I can be with this pair of CBB. 5 days in my tank and my male CBB is eating more aggressive every day. He is putting on weight. He is in better shape that my female at 5 days into my tank. Now the female is a fat little CBB. This weekend I am thinking of removing the Convict tang and get him into DT so the two CBB do not have an aggressive eater to share their mysis with. 2 cubes of mysis a day at about 30c a cube can get expensive fast. That is 60c per day (I spend 10.00 for a tray of 30 cube of mysis) and more than 1/2 of those mysis going into by hugely fat Convict.

The LFS got my on a choke hold and I cannot do anything about it. I can go only to order the similar amount of mysis for $1.50 at Live Aquaria. Shipping is a flat rate 29.99. I think i will bite the bullet and order 100.00 dollars worth of Mysis (including shipping, that will give me 40 trays. That will last me a long time.

Female

The Pair this evening before light out

 

[OrionN]

I am home all morning and able to observe my CBB pair for hours, to the displeasure of my wife. I am happy to report that they started to peck aiptasias in the tank. I am so happy that they are doing this and leave the rest of my corals and anemones alone. Both eat aggressively. I feed them this morning and both still full from hunting in the tank, along with eating aiptasia. I wish they would eat the aiptasia non stop, but this is not the case. Will see how long it take them to clear the aiptatia from my 40 breeder.

They already associated me with feeding, so they always make a beeline to me as soon as i get into the room.