Blue/hippo (Hepatus) tang spawning behavior

[djf91]

Hello everyone,

I have a 5-6 inch blue/hippo tang in my display and just recently added a small hippo tang that is about 3 inches in length, and rather than aggression I’ve noticed the larger individual displaying and doing what I would describe as a shaking behavior very similar to what clownfish pairs do.

From what I think I remember, this species starts low in the water column and does a rise towards the surface releasing eggs/sperm. I was just curious if anyone knows what specifically spawning behavior might look like, or courting behavior. I spent a summer interning at rising tide and worked a little bit with hippo tangs but can’t remember what courting looked like.

The display is an SPS reef measuring 72”x54”x30” tall. So probly not ideal height for the spawning rise but who knows. I know raising the larvae is a whole separate endeavor but was just curious.

 

[KrisReef]

<-Not like this

 

[ISpeakForTheSeas]

Here are two videos of them spawning in different tanks (most of the behavior take's place off screen to the left in the first one, but you can still see enough to get an idea from it - the second looks a lot calmer, but it's the same kind of behavior):


Edit: just to add, the yellow belly is the male in the second video.

 

[djf91]

Thanks for the videos. I’ll update if anything else happens. I would imagine they’re both too immature at this point to successfully spawn but who knows.

 

[djf91]

Also, these fish are Protogynous hermaphrodites, correct?

 

[ISpeakForTheSeas]

Also, these fish are Protogynous hermaphrodites, correct?

If I'm wrong, then hopefully someone will correct me, but I don't think so (at least not for breeding purposes, but I suspect not from birth on either). I think they are gonochoristic.

Here's a link* to a study where (as part of the study) they collected ~30 of these fish monthly for a year with sizes ranging from 30-180 mm and dissected them to gauge sex ratio in the population (~1:1), and to figure out the length of the fish at first sexual maturity (i.e. to figure out how big the female fish are when 50% of them can start breeding - 149.2 mm). To my understanding, the fish demonstrated distinctive male or female organs even at the smallest sizes collected (though the organs were indistinguishable without a microscope for all fish under the length of first maturity). After the length of first maturity, the organs were able to distinguished with little to no microscopic help.
*The link:

http://tvhdh.vnio.org.vn:8080/dspace/bitstream/123456789/20013/1/Huynh%20Minh%20Sang%20-%202018%20-%20Blue%20tang%20fish.pdf

Additionally, my understanding is that these fish are solitary until breeding time rolls around, and they then get together in groups (and possibly pair off once in those groups - I've only seen once source that says they pair off, however, and I haven't looked for too many more) to spawn. Since they don't live in groups regularly, but they do come together to spawn, it would make sense to me that they don't change sex, as they likely wouldn't need to in order to avoid aggression (since they don't live together), or to partner up/just join in the fray (so to speak) in one of these breeding groups.

Again, if I'm wrong, hopefully someone will correct me, but that is my current understanding/guess with these fish.

 

[vetteguy53081]

Hepatus tangs will shake and shimmy around each other when paired off and release floating eggs and lots of them if they spawn. The babies are very sensitive to water conditions making them prone to disease ( the challenge).
They are indeed hermaphrodites and it is as simple as dropping a pair together for pair-off

 

[djf91]

Hepatus tangs will shake and shimmy around each other when paired off and release floating eggs and lots of them if they spawn. The babies are very sensitive to water conditions making them prone to disease ( the challenge).
They are indeed hermaphrodites and it is as simple as dropping a pair together for pair-off

I remember the challenge being first foods….ie.: parvo.

 

[vetteguy53081]

I remember the challenge being first foods….ie.: parvo.

Recent captive bred have eaten copepods and rotifiers

 

[ISpeakForTheSeas]

Yeah, Parvocalanus crassirostris pods exclusively thrice daily from day 3 to day 12, then enriched rots added at day 12, powdered food at day 20, and BBS at day 21.

https://www.researchgate.net/publication/316929264_First_Record_of_Captive_Larval_Culture_and_Metamorphosis_of_the_Pacific_Blue_Tang_Paracanthurus_hepatus

The eggs are quite sensitive to parameters and the broodstock diet (if the parents' diet isn't good enough, the yolk won't keep the babies alive long enough for them to survive).

 

[djf91]

The two hippos have grown quite a bit in just the last several months. The larger is still somewhat aggressive towards the smaller but at they same time they do seem to spend a lot of time swimming together without aggression. The larger individual is the boss of the tank and aggressive towards everybody.

Last night, with just the blue leds on before lights out, the pair seemed to be swimming along side one another and the smaller one looked to dart up to the surface and may have released something, however the larger individual did not follow.

Ill see if I can get a video.

If these two were the same sex, would they still be going through the motions like this?