Last Updated: 2/5/09
Keeping other species of fish with goldfish
Story of how my goldfish and catfish "got along"
There are literally a hundred varieties of prepackaged flakes, floating pellets, sinking pellets, and many other sorts of goldfish foods. I will not go into them here. Most are very good. I like to feed variety. As the staple food for goldfish in aquariums, I use Tetra goldfish flakes. In my main pond, all the fish mostly get Pond Care summer pond food floating pellets. For fancier, more valuable fish and those with bigger wallets, the Hikari brand goldfish foods are very good. I do not want to delve too much into commercial goldfish foods. The purpose of this section was to discuss problems with feeding and feeding fruits and vegetables.
Some fish, notably fancy goldfish with enlarged bodies like fantails, orandas, etc., often have problems with digestion and buoyancy. Some of these problems can be worsened by feeding dry foods to them. If the foods are too dry, they may expand in their gut causing gas, bloating, and buoyancy problems. To prevent this, you can pre-soak dry goldfish foods for a few minutes in some water before feeding.
It is often recommended to feed peas to fancy goldfish that are having problems with digestion and/or buoyancy. Frozen or fresh peas should be cooked and then peeled. I once fed peas but was too lazy to peel them. They got jammed up in the goldfish's mouths. However, for huge goldfish, this probably would not happen. The peas act as kind of digestion medication. Goldfish scarf them up.
Goldfish will eat many vegetables, fruits, and aquatic plants. In the process, they may make a mess! Cucumber, squash, or zucchini can be cut in half and then into a few inch slice. Use a grapefruit spoon to scoop out the seeds. The resulting piece of food (which I feed all the time to my plecostomus) can be attached to a sinking veggie feeder (no longer sold) or anchored somehow (lead plant weights, plastic cable ties, fishing line, etc.). On the bottom, it could be tied to a rock. On the side of the tank, it could be attached to a veggie clip which is just a clamp on a suction cup. The goldfish will suck on those veggies (technically, those three are fruits). Attached to veggie clips, you can also try to feed goldfish leafy greens like kale, green leaf lettuce, etc. Do not feed iceburg lettuce. Lettuces will be shredded by the goldfish. Peas as described in the previous paragraph can just be dropped into the tank. They should float where the goldfish can suck them up. You can experiment with other fruits and vegetables. Your goldfish may like one that mine did not or that I never tried. I once tried grapefruit in my pond for the koi and goldfish. They were supposed to like it. They ignored it.
Goldfish love to eat aquatic plants. In fact, many of us wish they would not eat so much of them! When I had goldfish in my aquarium, any aquatic plant I put in there was quickly shredded. For feeding purposes, anacharis is a favorite submerged plant for them to eat. They will eat most submerged plants. The ones that lasted the long in my tank were onion plant and java fern. In the end, they even ate those. They are not supposed to eat java moss. Well (like our deer), no one told them that! In my ponds, the goldfish have many more plants and animals to choose from and much more room. So, they do not eat all the pond plants. However, I have tried repeatedly but cannot keep submerge plants like anacharis, cabomba, and hornwort alive for long. Even in submerged plant protectors, the goldfish find their way to eat them.
This is one of the most common and controversial questions about goldfish. Experts say that
you cannot keep other fish with goldfish because:
I believe that Numbers 1, 2, and 3 are not valid reasons for keeping other species of fish away
from goldfish. First, there are literally hundreds of fish that can survive 75 degrees F or less, the
goldfishes' preferred temperature range. Even so, in my ponds, the goldfish can live into the 90's
degree F, but only for short times. Thus, the temperature reasoning would only rule out such
high temperature fish as discus from being kept with goldfish.
While Number 2 has some value, I believe that all fish should be quarantined and treated for ick regardless, and that, in fact, goldfish are just as likely (and maybe more so) to give diseases to so called "tropical fish." The words tropical and coldwater are often misused. Some books define goldfish as tropical (obviously not!) while other define such coolwater fish as white cloud mountain minnows, rosy red minnows, guppies, zebra danios, etc. as tropical when in fact, they can survive lows from near freezing to about 60 degrees F, depending on the species. All of these mentioned fish can survive short periods in the 90's degree F but would not like to be above about 75 degrees F for more than a few months at a time in summer. Thus, we are back again to reason Number 1.
Reason Number 3 is also not valid. Goldfish produce no more ammonia or waste per mass than any other fish. The key is per mass. A one inch goldfish weighs more than a one inch say danio because the goldfish is a fat-bodied fish. There are many other species of fish that are also fat bodied. A goldfish's waste products are no more toxic than those exuded by potential tropical tank mates. I had a plecostomus with my goldfish (see below) and believe me, if anyone was killing anyone with waste it was the pleco doing it to the goldfish!
It is not until reason Number 4 that the true reason goldfish should be kept alone is seen. Even so, in ponds where there is a lot of room, even this rule does not stand up. I keep rosy red minnows, koi, orfe, common, and fancy goldfish all together in my 1800 gallon pond. I would not do so in a tank. "Tropical fish" tend to pick on goldfish while goldfish tend to eat all their food and "poop them to death" (simply because goldfish are larger and often kept in too small a tank, not because they produce any more waste per pound of fish). Large goldfish may eat small fish and certainly prefer to eat fish eggs and baby fish of any species. Let me recount my experience with plecostomus and goldfish. This is not to say that the same results would occur for others.
I bought a 50 gallon tank to put in my four goldfish from my old 20 gallon tank and a plecostomus from my old 10 gallon tank. I also bought four panda cories . I kept the heater at about 68 degrees F but it usually was in the low 70's. For more than a year, they all got along fine. Then, my adult female goldfish (named Fanny) developed a few rips in her fins from her overzealous suitors. As she laid on the bottom resting, the panda cories would suck on her wounds. The cories were not being aggressive or mean in any way. Fanny was unable to move fast enough, and the cories found some nice "food." Then, one day, I caught the plecostomus sucking on her side. That was it for my experiment. I put the injured goldfish in a breeding trap in the same tank so that she would receive clean water circulation. I treated her (and thus the whole tank) with a fungus killer since her open wound soon became a fungal forest. She had NEVER been sucked on like this before.
After two weeks in her net, I moved the cories and plecostomus to my 20 gallon, and then I released her. (The plecostomus was moved to the 10 gallon after a few weeks because he was overloading the other fish with his feces.) The injured female goldfish was still alive but hung around the surface and floor a lot. The males harassed her but did not seem to have further injured her. Both she and my tiny female (Wade) had only half of their tail fins due to the male goldfish, cories, and plecostomus biting them off. The plecostomus was my biggest problem. I could never destroy him or return him to a store to suffer. I also could not find a divider for my 50 gallon tank nor put him in my planted 20 gallon tank (he eats or uproots all plants but onion plant). Thus, he, all 7 to 9 inches of him, lived in the same, puny tank from whence he came until I set up a new 40 gallon tank in late 1998. By that time, he was 10.5 inches long. Fanny died months later on 11/23/97. She never grew her fins back which grew a black coating. Fanny did not move or eat for the last month of her life. The pleco cannot be fully blamed. I added a new goldfish (Ziggy) in 10/97 who got immediate fin damage with no apparent cause. The males must have been doing it. On 6/98, two rosy barbs with my pleco in the 10 gallon died. They were not sick and had overnight chunks out of their side. As Plecy (his name) was the only one with them, he must have killed them. He later did fine with other fish.
Years ago, when I knew basically nothing about keeping fish, a pet store employee told me it would be okay to add this long whiskered catfish to my goldfish tank (I do not know the species of this catfish; I am sure the employee did not either!). This catfish went right for the goldfish and began to eat off their fins as if was a predatory catfish. I immediately removed him and put him in the bathtub intending to return him in the morning. The tub drained over night but the catfish was still alive. He died a few hours after being added to more water.
Look under plecostomus for even more stories of plecos and goldfish and to learn more about my plecostomus. Anyway, the moral of the story: Do not add any species of fish with your goldfish (especially catfish) because you never know what will happen, and you may regret it. I certainly did!!
It is more likely that a small pleco will suck on large goldfish than the other way around. Years later, I put huge Plecy with small goldfish, and he did not bother them.
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