Tank Cycling

Tank Cycling

Hello Venus,

I’m goldfish sitting again. This time, just for 12 days. Since the pump and pond sponge was added last time, it appears that good bacteria were able to grow in the tank!

This is a 5.5 gallon tank with 3 small fantails. Unfortunately, I will not be able to upgrade the tank size as it is not my tank 🙁

Current readings are:
Ammonia=0, Nitrite=0.5, Nitrate=5, pH=7, KH=0.
(No GH reading until new tester arrives).

One of the fantails’ tail frayed before and apparently the tank was salted. When the tail healed, it became black. Current salinity is 0.03ppm. One side of the black tail is longer than the other. I’m not sure if it’s completely healed but I imagine this happened as a result of cycling. The top fin of that fish is also slightly torn. Should we add any treatment to assist in the fin/tail healing? Or is fixing water parameters enough?

Do you think we are in the middle or tail end of cycling this tank? With the current nitrite and nitrate levels, how often should I be doing water changes and how much water should I be changing? Should I dose Prime for the amount of new water added or the entire 5 gallon tank?

Since the KH=0 (very low mineral quality), should I add some backing soda? Our tap water also has close to no minerals and low pH. I have already ordered some small wonder shells to arrive next week. In the meantime, should I add baking soda to raise KH and then add the shells to maintain KH? Or just wait for the shells and rely completely on the shells to raise and maintain KH/GH? If I add baking soda first, how much should I add for 5 gallons?


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  1. Venus March 12, 2018 at 4:57 pm

    I emailed you, and yes, I regret not moving it to the tub, but SSG can result in the very same symptoms, and the fish would surely die if these gases were present, so you did the right thing. I’ve seen fish in the curled position for several weeks before treatment was offered that recovered. Every fish and every situation is different

    When a fish curls, it does so because the blood is thickening, and the body is constricting. It must be very painful. The fish should get relief in the deep water

    Should also warn you, once you add the Mean Green, you’ll need a flashlight to see the fish. You should be able to view it by pointing the flashlight on the side of the exgterior wall of the container

  2. emme March 12, 2018 at 3:40 pm

    So, the worst happened and the black-tail fish succumbed to nitrate poisoning.
    I found its body curled against the pump sponge today in the tank. I regret waiting last night and no taking it out of the tank sooner. I’m not sure how long it will survive now? It looked like it was having difficulty staying conscious and when it tried to move, its body was thrown with the water current from the pump and pushed toward items in the tank.
    I scooped the fish out of the tank and placed it into the deep chamber (20 gallons; 24″ deep) of water pre-treated with remedy from yesterday night. I also re-dosed with enough Prime for the whole 20gallons and hydrogen peroxide before placing the fish in. Before I left for work today, I noticed that the fish sank to the bottom of the chamber in its curled position but because it was too weak, its body also followed the water current and was pushed up and down in the chamber. Seeing the fish’s condition, I’m not too hopeful it will last more than a few days? How should I continue to treat this chamber tonight? Should I continue daily water changes? How much water should I change out/ replace?

  3. Venus March 9, 2018 at 8:10 pm

    Consistency in water changes, sponge rinsing and feeding are the things that matter. If you’re going to change something, do so very gradually

  4. Venus March 9, 2018 at 8:07 pm

    Are they all laying on the bottom, or just hovering above it, which is normal. Fish rest most of the night, and parts of the day. The older the fish, the more it rests.

    Okay. We might prepare for a spike after you increase feeding (slightly) and back off on water changes. I sell established pond pumps now and then. When I pull one from my tank, I feed a lot less, gradually working my way up. I’ve developed a feel for it, and never get a spike due to the fact. I think we all have this ability to feel our way through things, and although some parts of fish keeping are mater of fact; some aren’t

    If you damage the cycle? How will you know? There will be an ammonia or nitrite spike. As long as you’re getting zero for ammonia and nitrite with a healthy consistent reading of nitrates, the cycle is in tact

  5. emme March 9, 2018 at 1:17 pm

    Ok, I’ll back off on the h202 and water changes for now. I’ll feed small amounts of flakes again, yes. Though I really only started peas 2 days ago.
    I’ve used h202 for around 3days now. If I stop using it tonight and tomorrow and start your remedies on Sunday, will that be too much h202?
    I’m noticing that all 3 fish kind of bottom-sit/linger where the black-tail fish is in the morning. Is it because I am doing a lot of water changes? Hopefully I didn’t kill the cycle…

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