How is the condition in Kenya now?

My 3 inch Koi died yesterday due to Nitrite spike. I need to restore good condition on my 55gal tank.?

• My tank has two 1 1/2 inch Gold Fish and one 4 inch gold fish. It also has a 2 inch Israeli Koi. I am planning to donate the Koi alone when it gets bigger. I also have a small Plecostamous. The tank showed pH: 8.2, Amonia: 0 to 0.25, Nitrite: 2 to 5 and Nitrate: < 0.25. I did not do any water change after removing the dead 3 inch white Koi. Instead one of the Fish Shop guy suggested me to keep running the tank with the same water and add a fresh bottle of good bacteria and allow the tank to circulate the water with a pump for a week. So I just did that. My 5 fishes are in a Quarentine tank as of now with a heater setup and an aerator. They seem to be holding good but I feel that they are not happy due to a small tank size as of now in the Quarentine tank. I am hoping that the new bacteria will bring back the parameters back. Should I do something more to get the tank back in good condition? The filter pad which needs to be changed in the filter is new. The black mesh I did not touch assuming it will have some bacteria in it. The tank looks clean but as of now the water is little hazy due to the Nitrite spile. Please advice how I can get the tank to good condition quickly. Am I missing something still? Also given this fish community which looks always happy except for this mishap, how should I feed. I feed a pinch daily at night and it takes close to 4 or 5 mins for the fishes to eat all of them. But the shop guy said I over feed the fishes. He suggested that I should put food only so much that the fish consumes them in less than 30 secs!. Will the fish not starve if I do that? Given these 5 fishes (1 plecostomous, 1 small Koi, 3 gold fishes - shoubunkin) how much and how frequent I should feed them. If I dont put enough food will they not die? Always my tank looks super clean. Another question is how can I keep the tank water in good condition. There are lots of materials in the web but am not sure which one applies to me. I sometimes feel that I killed the Koi without knowing the Nitrite spike. I do see today that the Golden Koi has a small white dot in its side. Am not sure what it is? Did this Koi also get hurt due to water? If so how I can treat it? Lots of questions may be because I am paranoid. People who read this please help me out in this regard.

• Answer:

  personally i think it would be best if you do your own research and not completely rely on the store associate. most likely he cares less about the conditions of your tank than you do so research multiple sources. As for the the feeding of koi I am not too familiar with but several aspects of your tank stood out the first being the amount algae and how clean you said the tank was and the pleco you have. it could be that the algae ,a critical aspect of this ecosystem, has been depleted so much by the pleco hence a clean tank. Another factor you didn't mention that might be helpful is the amount of plant life which use up some of the nitrate. Im not very qualified to answer the question about the koi white spot but there are endless websites forums and other media where you can learn about it. p.s. better paranoid than dead huh?