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extreme_foolio asked in PetsFish · 1 decade ago

Cycling an overstocked fishtank possible?

Hello, my older brother is convinced that he can successfully cycle an overstocked tank. The tank is 5 gallons and is heated and filtered. It has 1 dwarf gourami, 2 african dwarf frogs and 4 neon tetras. We have a bet going because he won't believe me that it will not cycle properly and that ammonia/nitrite levels will always be too high.

He is convinced that as long as he vacuums the gravel weekly and does a 25% water change weekly (2 times a week if ammonia/nitrite gets too high) that the beneficial bacteria will build up enough to support this combination.

Is it actually possible for the biological filter to build up large enough to sustain these animals in this small tank? It has been 4 weeks and all the fish are fine, eating and healthy. Both his ammonia and nitrite levels are low but not 0. The biological filter will certainly take longer to go through its ammonia and nitrite spikes and complete but is it possible to successfully be cycled?

9 Answers

  • Ghapy
    Lv 7
    1 decade ago
    Favorite Answer

    4 neons, one dwarf gourami and a couple of adf's is not overstocking the tank for someone willing to keep to a weekly maintenance routine.

    I'm sure this must be by the 'inch per gallon' rule? I hope not - those rules work out sometimes but is misleading on many circumstances.

    All of his fish are small and compatible, with low waste compared to other fish. I would actually add 2 neons. He should have plenty of plant cover for all of them, especially with the gourami in the tank.

    Whether the cycle kills the fish depends on how close an eye he keeps on it and whether he can control the ammonia spike of all those fish in a new tank. The fact is that if his water changes keep up with ammonia production, which isn't terribly high with his fish in the first place, then he will end up successful. My vote woud be for him if he hadn't started with so many at once.

    I don't know how much your bro knows about fish but he seems to have some common sense, and a few things to learn about fish keeping.

  • 1 decade ago

    Yes, it will eventually cycle (assuming the filter's big enough), but it shouldn't be encouraged and he'll probably suffer multiple fish deaths. Even if he's made it this far, there's only so much poisoning the fish can take. They'll still be suffering from the affects of ammonia and nitrite. If he's cycling with fish, he should be carrying out daily water changes of 15% to keep the water quality as high as possible for the fish while the filter catches up.

    Does he use dechloronator? If not, I strongly suggest he gets a bottle and starts using it. Otherwise it won't matter if the filter cycles or not - the fish will still die of suffocation because chlorine builds up in the fish's gills along with killing the bacteria in the filter.

    The person above me has a point too. They should be in a bigger tank with a bigger filter.

  • 1 decade ago

    It is possible that the tank can be cycled because bacteria will continue to grow to balance the amount of ammonia and nitrite. The real problem is that the nitrate is going to be sky high unless he does a daily water change. Nitrate under 20 ppm is safe but over that is considered toxic (compared to ammonia and nitrite which becomes toxic over 0.5 ppm). If the nitrate is high, the fishes will live but die slowly.

    I had a overstocked tank: 30 gallons with 6 oto catfish, 6 black emperor tetra, 6 neon tetra, 8 blue tetra, 3 adult mollies, 5 four month old mollies, 6 adult guppies, 2 Gold Burmese Loaches, and 10 nerite snails. And I had 0 ppm ammonia and nitrite, but the nitrate was sky high and I had to change the water almost daily until I didn't have time anymore.

    Hope that helped.

  • Anonymous
    1 decade ago

    It's not a good way to do things, but yes it can be done.

    As long as he does enough water changes to keep the ammonia and nitrite below dangerous levels the tanks filter will eventualy cycle. The frequent water changes do slow down the cycling, but they should also keep the fish alive untill it's completed.

    Whether the tank is overstocked depends on the type of filter, how much water he is prepared to change and the temperment of the fish. But what he has should be OK.


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  • 1 decade ago

    In order to grow enough good bacteria for all those fish, he needs a lot more room. The tank just isn't big enough to support the bacteria. It's as simple as that. There's no way around it or to trick the cycle or something. Your brother doesn't deserve to have fish. His fish are being poisoned with ammonia right now this very minute.

  • 1 decade ago

    My brother kept 15 goldfish in a 10 gallon and i kept 10 gold fish in a 5 gallon and they cycled properly and had know problems. it was when i got a 20 gallon tank when my fish started getting sick and dying, That tank does not sound too crouded.

  • 1 decade ago

    i suppose technically you *can* maintain an overstocked tank, but it will require a lot more maintenance than a properly stocked one, and the inhabitants will be more susceptible to diseases and health problems. they can also suffer from stunted growth or deformities due to the lack of space. the beneficial bacteria will fluctuate considerably in between water changes and the tank will be cycling constantly, so he will never have a stable environment for his pets.

  • Its possible but very stressful to the fish and hell be lucky if none of them die

  • Anonymous
    1 decade ago

    cycle the tank with noo fish it only takes a week he can wate

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