“And that’s why birds do it, bees do it
Even educated fleas do it
Let’s do it, let’s fall in love—“
Whether you like it or not, your fish will join in the annual and natural event of regeneration. Fish spawning occurs when the temperatures in your pond reach 50º-70º. It may be a sunny warm spring day with the temperatures reaching the 80º mark, but unless the pond temperatures are between 50º-70º, spawning won’t happen. There are two approaches to handling spawning in your pond.
The “Do Nothing” Approach
The easiest approach is to “do nothing” and let nature take its course. Your fish will do all the work. They will date, mate and have children all on their own. The first part of fish courtship is not too different from the mammal world where the males chase the females, except this activity happens in water and usually in the morning. After several hours of chasing, it’s time for romance. At this point, things are a bit different. The female releases her eggs, and the male fish immediately fertilizes them by spraying them with milt. Milt is the seminal fluid of fish and other water-dwelling animals who reproduce by spraying this fluid, which contains the sperm, onto roe (fish eggs).”
That’s it for the parents. The eggs are “sticky” and those fortunate enough to stick to submerged plants such as Hornwort, Cabomba, and Anacharis have the possibility of developing and hatching in 3-7 days. The parents and any other fish and many types of aquatic insects will still consume as many eggs as they can find. Eggs which sink to the bottom of the pond will not hatch. They will be consumed or succumb to a fungus as the pond debris settles on them.
This “do nothing” approach may seem heartless but it is how Mother Nature has been operating for millennia, only the luckiest, toughest and strongest eggs survive to hatch. Furthermore, a mature female goldfish lays anywhere from 500 to 1,000 eggs. If every egg survived, the limited space of most backyard fish ponds could not sustain the population. In short time, the entire ecosystem of the pond would “crash” and all the fish, including the parents, would die.
You can increase your chances of baby fish survival in the “do nothing” approach by doing a “little something” and that is to have plenty of submerged grasses in your pond. As described above, those eggs that were able to stick to the grasses have a better chance of hatching and surviving predation.
The “Do Something” Approach
The second approach to fish breeding in a water garden, involves a bit more effort on your part. You will need to set up a nursery tank (an old child’s wading pool filled with water from your pond works great for this purpose) and purchase spawning mats. The spawning mats, made of a fibrous material, function in the same manner as the submerged grasses, the eggs will stick to the fibers. Spawning mats should be suspended approximately 6” beneath the surface of the water. The male fish will chase the females, leading up to the big moment when the female will rub her abdomen on the mat and release her eggs. The males will immediately fertilize the eggs.
If you are interested in raising a large number of fry (baby fish) at this point remove the mat to a nursery tank filled with pond water. It’s a good idea to cover the tank to keep birds from feasting on the young fry. Be sure to suspend the mat in the water column. Don’t just drop it on the bottom. Set up a simple filter and add lots of submerged plants to the nursery tank. Feed your baby fish with crushed goldfish flakes. Your young fish are ready to add to your water garden when they are ½” to ¾” inches in length.