Lots of Fish and Lots of Plants – Living in Harmony

Published on January 10, 2008

Biogen Idec, San Diego, CA
Biogen Idec, San Diego, CA

Over my years as a pond keeping professional, I’ve often met individuals living under the impression that one cannot keep plants and fish together. Just as well, I’ve met the individuals that believe one cannot keep many fish of different species, both predator and prey, in the same pond. In the following article I will touch on how all of this can be achieved with simple planning. I will reference the featured pond, as it has been a complete success in achieving and maintaining this balance.

This pond is a beautiful 228,000-gal pond and stream on the property of Biogen Idec in San Diego, CA. It is five foot deep in its center over the biofilter, and has a nice depth of two feet around its perimeter to make for great planting areas. Its pump feeds a fountain, waterfall, and 200 foot stream. This pond is an excellent example of many plants and fish living harmoniously in a safe environment.

First let’s talk about planting, as this should be one’s first step in properly starting a new pond. The reason is that plants must become established before they can handle the inevitable mild abuse from the fish. Planting in most cases should be started in the spring or summer; it takes about two months for the plants to begin to flourish.

When plantscaping, always keep in mind that your desired end result is the harmony between the fish and plants. At Fishy Business we opt, in most cases, to keep all “ankles wet plants” freely planted on the pond bottom or on slightly raised beds of clay and lava rock. In this method of planting we notice more unrestricted vigorous growth of all aspects of the plant: vegetative, flowering and root. This freestyle planting also allows us to mix different plants together to create a very natural appearing living bouquet of aquatic plants. One can surely appreciate the beauty of bright white roots drifting about, but even more than this, the roots have a natural filtering quality, benefiting the water too.

Free planting works great in most situations, but in liner ponds the occasional cutting back of the root base of the plant can threaten the liner. So be careful when trimming in liner ponds. Another crucial element when plantscaping is creating shelter and hideaways, because no one likes losing fish to predators like the Great Blue Grimreeper, aka the Heron. This can be achieved by raising those large planters on blocks or large flagstone islands. (Both of which I’ve done in the featured pond.) Other good methods include the use of large flagstone pieces to create underwater raised planting shelves that double as caves for fish. Another method to be noted is the floating plant island, such as the one by Maryland Aquatic Nurseries. The fish will appreciate all of these methods when a hungry raccoon visits the pond. But by far a fish’s best defense is good depth; a four foot minimum in the deepest area is key.

Also proper habitat for each fish should be considered when plantscaping. In the wild koi or carp prefer spending their time around marsh plants as they roust around in their thick roots and even heavy themselves into the shallows in the breeding season to lay eggs. The mosquito fish spend their time in the very shallow areas and pools within the thick plantings in areas safe from harm. The bass and bluegill frequent the area just off the edge of any planting or structure, but also require large open areas for nesting in which they can establish territory. Catfish prefer dark caves or thick root beds in which to hide throughout the day. The larger hi fin sharks tend to constantly move about the pond munching on algae and debris, but this can’t be said for all; small hi fin’s do seek refuge on the under sides of lilies and fallen leaves. Point being, when planting, create the habitat that the fish need to protect themselves, keeping in mind that each fish has different needs.

The true aquatic plants (waterlilies, lotus, hawthorn, etc…) we typically plant in shallow-wide containers. Cement mixing tubs work well and custom-made wood planters for larger lily beds are what we’ve done here at Biogen Idec. In the shallow-wide containers, the bulbs and tubers can grow latterly as they were meant to in the wild. Also, with the shallow-wide containers transplanting, cloning, and thinning is a snap. This method also prolongs the process of the bulb becoming root bound in a round pot.

In addition to all of this, in the featured pond we have also freely planted aquatic herbs, taro, reeds, iris and even a small gunera in the stream to encourage negative filtration.

Now the plants have become well established. Their roots are well into the clay, they’re holding on to the lava rock. It’s time to start stocking fish. In this particular pond, Biogen Idec and I wanted it all; colorful koi, inquisitive bass, feisty blue gill, some big soulful albino channel cats, hardworking algae eating hi fin sharks, detritus processing cray fish, and old reliable mosquito fish.

When stocking such an array of fish, both predator and prey, one must get back to thoughtful planning. Knowing that a largemouth bass can and will eat anything up to a third its own size, the smallest creature one can add to the pond must be a third the size of the largest bass. By that principle I will generally add the omnivores and passive fish first: the koi, the hi fin sharks, mosquito fish, and small catfish. This is also a good time to add any crayfish, snails, or frogs. By adding this sort of fish first, it allows the fish time to become established and familiar with their new territory. This is very important so they can avoid confrontation in a familiar environment. If you’re a patient person, even better, wait a little longer and the fish will put on a little weight before their new hungry predator friends come.

Now that the more passive fish are established we can add the bass, bluegill, medium catfish and turtles if you desire. With this method of fish stocking the passive fish will always be larger (or large enough to avoid issues) than the aggressive fish. When adding the aggressive/predatory fish, no fish shall be larger than? – the size of the smallest passive fish.

In the attached photos you see bass, blue gill, koi, and hi fin sharks all schooling together around me as I take some under water photos. If all of these techniques are followed carefully with patience, the results will be a very diverse, beautifully planted, and busy pond for all to enjoy. On that note I’d like to thank Biogen Idec for the opportunity to provide them with such a beautiful pond. They are a shining example of a company with the desire to provide a tranquil, enjoyable work environment for their hard working staff.

When stocking in this method I have a few additional points and pointers. At this time in the process, the smallest koi is the same size as the smallest bass, with the largest bass being twice the size of the smallest koi. When choosing the koi initially, one should take care and be sure that the original koi added are of high quality as these will be the final koi living as well; most all fry born to the pond will be eaten. This is fine by Fishy Business because quality koi don’t often come from unorganized breeding, but more importantly, this helps population control and creates a balanced symbiotic relationship within the pond.

In our opinion this is good, this is what we are trying to achieve. It is an example of a natural self-sustaining environment. The bass and blue gill will eat the fry of all the fish we’ve added as well as the crayfish fry and even keep each other in check. Koi and hi fin sharks forge algae and eat the eggs and small fry of all the pond life, while the catfish will eat mostly the dead and sick fish. All of these elements combine to maintain a desirable and manageable fish population in a planted pond.

Another point to be made is in the importance of maintaining a practice of feeding the koi a high quality fish food to maintain their growth over the aggressive fish. In the featured pond I’ve been feeding them Emperor’s Choice, a custom blend available from Pacific Coast Distribution, to which I have been amazed by its results. I’ve noticed the koi always tend to take to pellet food better than the other fish, which is what we want. I would not be concerned with feeding the other fish.

After seeing step by step how harmony can be achieved, I’d like you to think of another kind of pond for a moment. Have you ever seen that large pond with two big lonely koi, ten big lazy bass and one hundred darty small bluegill and no plants. Well, take in the concepts of this article and that can be avoided.

Keep Ponding.

About the Author

Michael Hasey, Owner: Fishy Business of 7 years – custom pond & water garden building and service.

First personal pond: 18 years ago. I view my style as diverse and custom never conforming to any technique or product line. I am the pond professional for the person requiring custom/ show quality in a well-planned water feature.

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