Breeding Clownfish – A Guide for Hobbyists. Part 1

Breeding Clownfish Part One

Contents

Part 1 – A General Overview of Clownfish Breeding

Part 2 – Broodstock

Part 3 – Larval Care

Part 4 – Plankton Culture

Part 5 – Metamorphosis and Juvenile Growout

One of the most common questions that we get asked at AZaquaculture is “My clownfish just laid eggs – what do I do?”  Well, there are a lot of answers to that question.  What this guide will do is present a simplified version of the methods we use at AZaquaculture to spawn clownfishes and rear their young, while trying to eliminate as many of the energy intensive steps and pitfalls that may put new breeders off of the idea.  These are certainly not the only methods available, but we have found these to be time-tested and allow prospective breeders to still have a life while enjoying successes with marine fish breeding.  We hope that we can help as many hobbyists as possible to “give it a go”.  Many of the advancements in ornamental fish culture industry occur not in laboratories, but in the homes of hobbyists.  By encouraging the home culture of marine fishes, we hope that we can help spur the advancement of exploration in this field while at the same time, reducing the dependence on wild-caught fishes, creating a more eco-friendly and sustainable hobby for all to enjoy.

Breeding Clownfish – An Overview

Rearing clownfish can be a challenging, time-consuming, and sometimes frustrating endeavor, but for those wishing to expand their knowledge and try their hand at clownfish rearing, it can also be immensely rewarding. There is nothing like seeing your first rearing tank fill up with hundreds of tiny versions of their parents.  So, to begin with, we will present an overview of clownfish breeding and what you can expect along the way to that point.

Clownfishes were among the first ornamental species to be commercially bred in the 1980’s.  They remain the most popular marine fish and fortuitously are relatively simple to breed in captivity.  There are several reasons for this; they are demersal spawners (lay their eggs on the bottom or other fixed substrate), and these eggs give rise to comparatively large larvae.  They are also sequential hermaphrodites, meaning that they begin their lives as males, but as they pair up, the larger or more dominant fish will change sexes to become a female.   So, if purchased as juveniles, any two clownfish of the same (or similar) species can become a fertile pair.

Clownfishes typically reach sexual maturity at an age of 8-18 months.  As they approach spawning age, they will vie for dominance, which can include some chasing, fighting, tail nipping, and a general bullying attitude by the victor.  Once dominance has been established, courtship behaviors will commence.  This includes vigorously fanning the bottom as they clean potential spawning sites, side-by-side swimming with the typical clownfish “waggle”, and a decreased (although not eliminated) level of aggression.
Spawning occurs during daylight hours and a small clutch of eggs is laid usually on the underside of a rock or other solid base.  The nest is usually compact, measuring 1-3 inches in diameter, circular, and comprised of small red or orange eggs, each smaller than a match head.  A typical nest may contain 100-300 eggs for the smaller species such as percula, Amphiprion percula, and false percula, Amphiprion ocellaris species, or up to several thousand eggs for maroon clownfish, Premnas biaculeatus .

Clownfish eggs will hatch after dark, 6-9 nights after they are deposited, releasing a swarm of small 3-5mm silvery larvae.  Clownfish fry will not survive in the parental tank.  Filters, corals, and even hungry parents will make short work of these delicate hatchlings.  Newly hatched fry can be moved with a siphon to a larval rearing tank (usually a bare bottomed 10 gallon with only an airstone and heater inside), or the entire nest can be moved to the larval tank on the night of hatch.

Larval clownfish feed on plankton of very specific sizes.  The standard first food for clownfishes is marine rotifers Brachionus plicatilis.  These are tiny gelatinous creatures that have little nutritional value.  Rotifers must be “gut loaded” with microalgae to make them nutritious enough to be used as a clownfish prey item.  Depending on the species of clownfish, larvae will consume rotifers exclusively for the first 4-8 days of its life.  Once the clownfish babies grow large enough, they are transitioned onto a second food, Artemia spp. (brine shrimp).  Atremia are much larger and more nutritious than rotifers.  Artemia are purchased as dry cysts that can be hatched into nauplii and fed to the larvae.  During this time clownfishes can also begin their transition onto frozen and dry feeds.

At an age of 10-14 days clownfishes will undergo metamorphosis.  This is when clownfish “earn their stripes” and will begin to look like real clownfish.  Metamorphosis can be a tough time for the fish, and losses can be heavy if they are not managed carefully.  Once they have made it through metamorphosis, the hard work is over.  Filters can be added and the fish can be completely weaned onto prepared foods.  Then it’s time to relax and watch your new babies grow into a “herd” of clowns.  By an age of four months, clownfish should reach a size that is safe to sell to fish stores, trade with hobbyists, and help to feed your aquarium addiction.

In the next part of this series we will look at selecting your broodstock and preparing a suitable tank for clownfish breeding.  In the meantime, here are some links to additional sources for information on clownfish and marine fish breeding.

Clownfishes by Joyce D. Wilkerson
– A fantastic and thorough guide to keeping and breeding clownfishes.

Conditioning, Spawning and Rearing of Fish With Emphasis on Marine Clownfish by Frank H. Hoff 
– For those interested in some deeper science of clownfish culture, or for those interested in opening a commercial hatchery, this is indispensable.

Plankton Culture Manual – Sixth Edition by Frank H. Hoff 
– The companion to Hoff’s clownfish book, this covers in great detail the culture of many marine plankton species from microalgae to rotifers, artemia, copepods, and even mysids and daphnids.