Explain this strange aggression?

[JaneG]

Hello,

I have a 20g nano tank with a 20g sump. In this tank I have a pair of ORA Spotted Mandarins (before I am asked, I feed them 3-4 times per day and have heavy filtration - I clean my skimmer cup 1-2 times per day). I've had this pair for about a month now - the female was added the night before the male, however. Anyway, basically, the female is aggressive to the male during the day and will chase him off if she catches sight of him. However, if I only have my blue LEDs on or if the tank lights in general are off, she will leave him alone - even kind of follow him. I know it's possible to keep a pair in a nano: on MOFIB it even says that a pair can be kept in as little as 20g or so (plus my tank has a lot of SPS and plenty of territory). Additionally, I know I have a boy and a girl because the female is quite gravid. They're about the same size as well: if anything, the male is larger. Any explanation as to why this is happening? :worried: Thanks!

 

[small alien]

The way to sex mandarins is by the first dorsal spike. Do you have pics of both fish.

 

[evilfrog]

you sex them by the long first dorsal spike.she may also be trying to outcompete the male for pods and other food.are they eating frozen mysis?

 

[SushiGirl]

So the female is pregnant?

 

[snorvich]

The way to sex mandarins is by the first dorsal spike. Do you have pics of both fish.

this

 

[Rybren]

Male..

Female...

 

[snorvich]

With the "green spotted" mandarins the dorsal fin spike is less pronounced on the male. Still sharp, but not extended as in the picture. NICE pictures by the way! Are they yours?

 

[JaneG]

I am positive I have a male and female. I've seen photos of male and female mandarins and I can see the difference quite obviously (he's brighter in general, he has a dorsal spike that she completely lacks and has for the whole time). I believe the LFS ordered them in from ORA as a pair. She's definitely gravid/ripe - her belly distends far out making her look like she swallowed a small gum ball. The male even displays to her sometimes at night - no spawning or rising yet, but he does open his fins at her and acts excited. I could post pictures and maybe a video if I need to?

The aggression is not to the point where I need to get rid of her any time soon (he doesn't seem too stressed from it), but still kind of frustrating as I like my tank to feel peaceful. I can understand generalized aggression from a pair of mandarins - maybe she needs more room (but I have seen it done before even in a nano without aggression) - but why does she ignore him when just blue LEDs are on (even at full blast) and why is SHE the aggressor? I can turn up the whites to the bare minimum - but if I go any higher she will immediately chase him off. If she's about to charge him when both whites and blues are on and I flip off the whites, she leaves him alone. :mad2: I am considering to just have blue LEDs on for longer than the whites just to try to minimalize aggression. I am fairly sure they're getting enough to eat: they get a mixture of capeline roe, shrimp eggs (Nutramar Ova), Hikari mysis, and NLS pellets 3-4 times per day in quite big quantities. Their bellies are both very full (of course the female is, but the male's belly even sticks out after he's pooped). Thanks for the help!

 

[small alien]

Ime pairs of dragnets are not the most peaceful couples. Not sure what to suggest. If the male were aggressive, I'd suggest a second female.

 

[small alien]

Evilfrog is right about hunger causing aggression.

 

[Rybren]

NICE pictures by the way! Are they yours?

Unfortunately, no, they're not.

 

[JaneG]

Evilfrog is right about hunger causing aggression.

I tried bumping up the feeding for about 2 days once to 5-6 feedings and it didn't help...I don't think they're hungry as they have a lot of pods (I have a fuge and porous LR) and I feed them sooo much? I just don't understand why she leaves him alone with just blue LEDs.

 

[snorvich]

I tried bumping up the feeding for about 2 days once to 5-6 feedings and it didn't help...I don't think they're hungry as they have a lot of pods (I have a fuge and porous LR) and I feed them sooo much? I just don't understand why she leaves him alone with just blue LEDs.

My speculation (guess) is that she feels the blue lighting is a precursor to dusk.

 

[JaneG]

My speculation (guess) is that she feels the blue lighting is a precursor to dusk.

Ah...I guess they spawn near that time, so she wouldn't want to chase off a potential mate? Makes sense to me! I am thinking that I'll just keep my white LEDs on for a minimum. I've ordered optics for my LEDs which should increase intensity considerably, so I think I'll start then. Luckily I don't mind the look of just blue too much. Thanks for the explanation! :strange: