Freshwater fish question.

[Shawn O]

I know this is a SW site but figured to give this a shot since there are so many here with FW experience. My favorite chinese restaurant has had a 20 gal tank with about 6 or 7 Koi in it for several years. I recently went in to pick up dinner and his Koi are getting huge. The things are at least 7" long now and the tank looks extremely overcrowded. I felt so bad for them that I offered to donate one of my extra 55s to them if the owner wants it.

What do these things eat in nature. I'm curious what other CUC inverts can be in the tank with them without being eaten.

Also, I guess that the gravel will likely need to be rinsed out real well and most of the original water should be reused. Should they use RO, RODI or spring water to make up the difference?

[Sk8r]

Conditioned tapwater is ok. Koi eat koi food (Hikari is the best, imho) but they will also not turn down a stray lizard, small fish, etc, if really hungry. I don't know how they are with snails, but the Japanese trapdoor snail or the apple snail might survive. Mostly they need really good oxygenation and ideally, good filtration is nice to let people see the fish, though the koi are often in murky water. In nature they eat algae. They will 'hibernate' in winter, but in an indoor tank, they'll be active and growing. Lifespan is up to 235 years, max length about 3', but that's in a huge pond with ideal conditions.

[Dogshowgrl]

Not to many inverts that can be added. RO waste is fine, RO is fine but over kill. Dechlorinated tap is fine if mixing with existing (we use well water straight). They are part of the carp family and root for inhabitants of the silt river bottoms. Snails, inverts, and plant matter and all part of the wild diet but we feed a lot more plant matter in captivity. I know from experience they love snails, pet stores use them to clean tanks when snails take over.

No good deed goes unpunished. ;)
Best of luck!
Thank you for watching out for all fish.

[Cujo13]

Good advice above. We have had a 5,000 gallon koi pond for years. I bring them into the basement and house them in a 300 gallon Rubbermaid during the winter. They always look forward to Spring. True Japanese Koi strains will reach 36 inches, domestic around 24 inches. Love watching them propel their body up on our lower waterfall to clean the algae off. Otherwise just plain Koi food. The most ideal place would be a muddy pond where they soak up minerals and the like. The issue is they need a lot of space. 20 gallons is a joke. Good for you for trying to help them out.

[ericarenee]

i agree with everyone above. the only other comment i can make is if they have Live plants do not us DI Water.. Water ran thru sediment and carbon filter only in my opinion..
I KNOW With out freshwater planted tank i do 15 gal water changes twice a month and at once time was using di water and the plants started getting holes in them... When we looked it up it was lack of hard elements in the tank.
i think the planted tank is more work then reef .thou ours is very basic and low tech unlike the reef tank

[Shawn O]

OK, no snails. At least not expensive snails. How about shrimp? I know of an underground spring I could tell them about. Plenty of minerals but I'm not sure if any heavy metals are in it. Thanks folks.

[Sk8r]

Lunch, real fast. Frogs, likely the same. I'd just say a regimen of partial water changes. What you could do is texturize their environment---maybe here is a place some plastic plants could be useful, providing fronds for them to brush through, fuss with, lip over---they're great hedonists, and like to mouth things and rub up against stuff.

[Cujo13]

Keep it simple. They are like large goldfish. Good filter, food and substrate. No heater needed. FYI, they love watermelon, see pic.

[ericarenee]

keep it simple. They are like large goldfish. Good filter, food and substrate. No heater needed. Fyi, they love watermelon, see pic.

1+

[Shawn O]

Thanks for the replies, folks. I'll call the owner and offer the tank and a home-made stand, once I can throw one together.

[snorvich]

Conditioned tapwater is ok. Koi eat koi food (Hikari is the best, imho) but they will also not turn down a stray lizard, small fish, etc, if really hungry. I don't know how they are with snails, but the Japanese trapdoor snail or the apple snail might survive. Mostly they need really good oxygenation and ideally, good filtration is nice to let people see the fish, though the koi are often in murky water. In nature they eat algae. They will 'hibernate' in winter, but in an indoor tank, they'll be active and growing. Lifespan is up to 235 years, max length about 3', but that's in a huge pond with ideal conditions.

This. Mine quickly reach about 20 inches, then slow down a bit although I have three that are about 30 inches. I only feed Hikari Gold, but they do eat algae and the roots of plants in the pond.

[snorvich]

Oh, and water change of 100 gallons per week although probably not necessary.