Changing photoperiod and temperature to encourage/discourage breeding?

[LordJoshaeus]

Hi everyone! I was doing some research yesterday and found at least several 'tropical' marine fishes in this hobby that seem to undergo noticeable seasonal changes in photoperiod and temperature - Gobiodon atrangulatus, for example, I found to generally have summer temps in the low to mid 80's fahrenheit and winter temps from the high 70's to as low as the low 70's, with photoperiods being around 14 hours in summer and 10 hours in winter. With that in mind, could I control when a saltwater fish decides to spawn by simply changing the tank's temperature and photoperiod over the course of the year? I did read at least one article on reef to rainforest that stated that the New England Aquarium, when going to breed the blue reef chromis, increased the photoperiod and temperature of the tank the broodstock was in to 14 hours and 80 fahrenheit respectively and got them spawning within two weeks. Thanks

(PS...here is the aforementioned reef to rainforest article; https://www.reef2rainforest.com/2016/12/31/breeding-the-blue-reef-chromis/ )

 

[Doctorgori]

Just curious...lurking

 

[mort]

It's an interesting topic and one I can really only guess at but I think this is more important with corals and certain fish species that definitely follow the seasons to spawn on mass (like some groupers). I'm not really sure it matters as much with the average reef fish that tend to spawn regularly, sometimes daily, when condition allows. If you look at damsels (clowns as well), small reef wrasses and dwarf angels, it is quite easy to witness breeding behaviour just by keeping them in groups and feeding well. It may be a good tool for fish that are less likely to spawn but I can't see it working in the same way as for river species that sense seasonal floods etc.

 

[ichthyogeek]

I think with corals it has to do with other abiotic factors (moonlight, tides, changes in water chemistry) as well...and I'm fairly certain I've heard of Elacatinus having a seasonal spawning schedule as well...

Keep in mind that a lot of the reef fish being looked at for breeding are usually localized around the equator. This means a constant number of hours of sunlight and a constant number of hours of darkness as well.

With more temperate species (Catalina gobies, etc.), I'd be more than willing to assume that changing the temperature and lighting schedule would lead to increases/decreases in spawning behavior though...

Now...I don't believe you could control exactly when (by day) a fish will spawn. Yet. It'd take a little bit more experimentation/development of reef equipment to do that. But, you could choose to let the fish know whether or not it's breeding season. Cooling the water temperature down (like, say 75), decreasing feedings (1-2x/day), and decreasing lighting schedules (8 hours) should turn the "make babies" switch in their brains off. Conversely, making the water temperature warmer (80-82 F), increasing feedings (3-5x/day), and increasing lighting schedules (12 hours) would probably turn the "make babies" switch on.

 

[pcon]

There are many species which are triggered by fluctuations in lighting schedule and temperature. The venusta angel is the one that comes to mind first. Spawn in the fall so are triggered by decreasing light intervals and temperatures.

 

[Superlightman]

I recently raise the temp to 80 and the light is 14h and my clown fishes and gobidion both started to lay eggs for the first time,coïncidence ?

 

[JPM San Diego]

Years ago (1985 to 1995) I had a pair of Ocellaris clownfish. Over the decade they were housed in various aquariums with various set ups. Whenever I used a timer to turn the lights off and on, thereby giving them a precise circadian rhythm, they would spawn every two weeks. Whenever I turned the lights on and off manually, still shooting for the same on and off time, they would cease spawning. It was an interesting and reproducible observation.

 

[diverpat]

We use light and temperature to get fish to spawn in commercial aquaculture. We call it the photothermal regime. I work with temperate species so the seasonal changes are more pronounced than tropical reef fish. You can also manipulate the photothermal regime to trick fish into spawning out of season or prolonging the spawning season. This is vital in aquaculture so you can spawn year round or manipulate spawning times to meet a specific schedule.
For growout to market we try to have a constant photothermal regime to inhibit spawning. You want all energy to go into growing muscle and not gonads. It’s not that reliable though, the fish still have some internal clock and they know when it’s time to get it on.