|Feeding and Underfeeding Koi and Goldfish
Multiple variables influence WHAT you feed, how MUCH you feed, and whether you even NEEd to feed Koi, goldfish, in different kinds and sizes of ponds.
The majority of hobbyists, if they were to make a feeding mistake, would overfeed. This is because the feeding process is arguably the best time you have with your fish. At feeding time, Koi come up to eat so you can see them, and anyone with a maternal instinct will thrill to watch their favorite fish engulf food with such Koi-ish zeal. Overfeeding is engaged anytime the fish are eating more than they need. So, for a fish farmer with a mud pond full of small fish he's trying to grow, he would feed about five to seven times per day. That would not be overfeeding. But in a typical ornamental pond with a reasonable collection of fish, that feeding rate would be excessive and the wastes therefrom would strain the limits of what can be biological reduced. Means: You water quality will decline.
Fish that are overfed in typical ornamental pond facilities will eventually develop ponderous bellies and begin to look a little bit like tadpoles, with the big body and the wispy tail. That is not a terminal event for the fish but the impact on the liver and other internal organs can and will be severe. Farmed fish that have much more room in lakes or large ponds can be fed considerably and they will not develop as much obesity as reguar backyard pond fish.
Fish should be fed no more than three times per day. In cooler water they should only be fed once per day, if that. In much warmer water, three times per day is not 'crazy' however, you have to be wary of bacterial blooms (cloudy water and low oxygen levels) if you feed heavy and there's a lot of waste.
Fish should be fed for about five minutes per feeding. If they don't come up and eat voraciously, they are telling you that they are too cold, or too warm, feed light. If they come up and "hit hard" you can sprinkle food on the water for five minutes as long as there are fish there to carry it off. Pretend it's a game, NEVER LET IT FLOAT. So, feed the fish as they approach and let them carry it all away, leaving none to float into the skimmer or filter.
Sometimes a person is very busy and they may neglect to feed the fish every day. This only impacts certain groups of fish. The very large fish in summer will rapidly lose weight as their metabolism is working optimally but there aren't enough calories for their big bodies. Very small fish which need to grow will also be stunted or die. Fish in ponds with natural forage and some plant material will help themselves to nature's bounty. Fish in indoor or liner ponds without additional access to forage will lose condition. If you fish are growing about a half-inch per month, you're feeding enough.
If you have a Goldfish or Koi that is NOT growing a half-inch per month you are either underfeeding, you are keeping them in too small facilities, or the food is not adequate to push growth. Many fish grow one inch per month. Even relatively slow growing Ranchu's can be pushed to one inch per month in large facilities and fed fresh proteins.
Signs of underfeeding include: Heads wider than bodies, slightly sunken eyes, a kink at the base of the tail, poor color, thinness, trailing white stools, and inactivity.
Do You Feel The Need To Feed?
Not every pond has to be fed. I know it sounds amazing but it's true. And there's a converse too. I've heard Aquascape installers say that their ponds never need to be fed and that's equally wrong. If you've stocked with koi, chances are you will need to feed something. If you stock heavily with Goldfish, you will probably need to feed.
But if you have Mud bottom ponds with freshwater feeds and a 'bug light', you have arguably "handled" the fishes' feeding requirements. This is because in spring fed mud ponds, there's always something to eat. Either a variety of amphibians in the Spring and sides of the pond, or copepods and worms on the mud floor of the pond. If you suspend a plain light bulb fixture over most ponds and run it at night - insects will be attracted to the light and fall into the Koi's waiting mouths. This advice does not hold true for stocking farmers who have many mouths to feed in such ponds. I hope this brings home the concept of natural forage. Does your pond have natural forage?
What follows is a brief discussion of how pond "type" influences feeding requirements.
Very sizeable Aquascape ponds
I have a friend named Greg Wittstock who has an Aquascape pond of probably an acre and a half. Maybe larger. And in this pond there is a teeming ecosystem of turtles, fish, plants, insects, and amphibians. If a fish were to die of starvation in his pond, we would have to assess the fish as being brain damaged. There's plenty to eat. Many of the large Aquascape installations will have a goodly amount of live food and plant material for the fish to be sustained on. This is great from the standpoint that you can feed conservatively, and if you are ever away or forget to feed the fish chances are they'll find something juicy in the gravel or they could prune your plants. Foraging in the gravel is an important way that fish prevent that very gravel from stagnating. (Or you can toss a pair of boisterous kids in for a weekly summer swim like Ellen B. in Batavia does.)
"Proper" Koi ponds are engineered to be easy to clean, and they meet the housing needs of the fish over any other ancillary purpose. What defines a "proper" koi pond is dependent upon the ego of the person you're talking to. The more inflated the ego, the more narrowly you will find "proper" is defined. You might also notice that "proper" among the most bellicose of pundits is ONLY equivalent to what THEY have installed in their yard, to the exclusion of all other obviously "wrong" concepts.
I digress, but thanks for allowing me. A proper Koi pond by any definition is a rather sterile above ground or attractive in-ground container of water lined with rubber. The filtration system is usually copious, but so effective as to render water that is "gin" clear. This is one of the two main ponds I have, and in truth I enjoy it for my finest collector-Koi because it's "All about them" and they really thrive with that kind of environmental control. As a high performance machine, the filtration requires regular adjustment, backwashing and tweaking and the water requires regular testing because there is no stone to buffer pH. The fish show up beautifully on the black rubber background and cleaning the stuff off the bottom is as easy as pushing it to the bottom drain with a hose with fish in place. There is no Spring cleanout. Instead, my investments in time are small, but almost daily.
In my case, the "proper" Koi pond is a fairly obtuse, ugly box of water otherwise. I mention this in a nutrition article because "Where is the natural forage?" There is very little.... I must supply ALL the nutrition to these fish and so I have complicated, but gained greater control over, my hobby.