“Harem” style tanks have become quite popular and have allowed hobbyists to maintain a larger number and diversity of clownfish than the traditional single-pair-per-tank historically recommended.
Here are 7 tips to keep your harem happy and healthy.
1) Pick Your Female
All clown fish are born males, When it finds itself in a dominant position (in a anemone or somewhere in a tank, it has a hormonal transition and becomes female. (a one way trip). During an approximate three week transition it can double or more in size, and once transitioned accept a submissive male as a mate. Dominant females typically tolerate submissive juvenile males “in attendance”, which in the wild means hanging out under the anemone.
One way of setting up a harem is to select or develop a dominant female. Keep a juvenile male in the tank by itself for a month or so, and then introducing immature juvenile males of a small size..
2) Start Small
Start with smaller clownfish. This will put less strain on aquarium's water treatment system and reduce stress on your clownfish who will more easily acclimate to others when they are younger.
3) Mix it up!
You can mix different types of Ocellaris/Percula (including any of our designer varieties) provided all are roughly the same size and added all at once. While a popular idea, there is no merit to the notion that fish need to be from the same brood stock pair although we can certainly accommodate requests to do so.
4) Maintain Water Quality and Temperature
it is important to monitor water quality (especially ammonia, nitrite, nitrate, and pH) over the first few weeks, increase filtration, and do waterchanges as-needed to keep things healthy as the tank adjusts to the increased bioload of the new fish.
Poor control over water quality and temperature increases aggressive behavior or perhaps they just become cranky just like people.
5) Increased Feedings
Increase your feed rate to at least once daily. We recommend .8 mm SA Hatchery diet for all of our Clownfish. Proper nutrition increases fish health and reduces aggression.. both good things!
6) More Anemones
Anemones are great for harem tanks, but they aren’t required – you can have as many as you like, but I’d suggest having either 3 or more or none.
Having a single anemone is going to lead to territorial problems as the dominant fish will claim the space.
7 And a Big Tank
At least 60 gallons. Give them space!