Medaka and a White Cloud Minnow Crammed Into a Tiny 3-Liter Tank — 5ch: “Basically Keeping Them in a Toilet”

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The story

A post on 5ch’s Newsspeed VIP board described how, three days after putting one medaka (a small Japanese rice fish) and one white cloud mountain minnow (a small hardy minnow, called akahire in Japanese) into a tiny 3-liter tank, the water started to smell. The tank doubled as a plastic case normally used for keeping insects, with no filter or aeration installed. White cloud mountain minnows naturally prefer to swim in groups of three or more and are generally said to need at least 10–12 liters even in a small setup, so the thread argued over how much water was actually needed, how much waste the tank could handle, and whether a filter was necessary. In the end, the poster decided to move the fish into a 24-liter tank.

What people said

1AnonymousSep 13, 2026 10:42
Morning of day three
Something reeeeeks!!
But it'll be fine, right!
3AnonymousSep 13, 2026 10:43
Two fish in 3 liters should be totally fine
Probably just used tap water straight, huh
5AnonymousSep 13, 2026 10:44
Re: #3
Planning on racking up more victims?
14AnonymousSep 13, 2026 10:48
Makes you wonder how those goldfish bowls in picture books are supposed to keep the fish alive
15AnonymousSep 13, 2026 10:48
Re: #14
It's gotta be some ultra high-performance goldfish bowl lmaooo
16AnonymousSep 13, 2026 10:48
My mom bought some medaka and is keeping them in a snack container
I offered to buy her a small tank with a filter but she says she doesn't need one
I bet she's gonna kill these ones too
18AnonymousSep 13, 2026 10:50
Re: #16
Even with a filter she'd probably kill them anyway, so it's the same either way
Waste of money
(harsh lol)
17AnonymousSep 13, 2026 10:48
Is this the guy who keeps killing fish because he does his aquarium based on AI advice?
25AnonymousSep 13, 2026 10:56
White cloud mountain minnows are schooling fish, so it's recommended to keep 3 or more (5–10 or so if you want to really enjoy watching them school).

Rough guide to numbers

Minimum: 3 or more is best to prevent fighting and stress and satisfy their schooling instinct.

For a nice display of schooling: 5 or more, ideally around 10, gives you an impressive school to watch.

Guide by tank size: for a small tank (roughly 10–12L of water), around 3–5 fish is a manageable number.
26AnonymousSep 13, 2026 10:57
Re: #25
Well, of course that's only if you've got a filter, live plants,
and a proper substrate set up too

I wish you'd have spelled all that out lmaooo
27AnonymousSep 13, 2026 10:59
People who spout half-baked advice should realize they're just as guilty, you know?
'One fish per liter,' give me a break
That's only allowed under seriously good conditions
28AnonymousSep 13, 2026 11:04
Re: #27
Oh, by the way, this ID is Re: #1
33AnonymousSep 13, 2026 11:10
Think about it calmly
The waste tolerance is way too low
It's basically like making them live in a toilet
46AnonymousSep 13, 2026 11:38
White cloud mountain minnows and medaka don't even match on temperature or pH
48AnonymousSep 13, 2026 11:39
Re: #46
They're pretty much the same actually
It's just that white cloud minnows really want to school and need swimming space
And not knowing that, I put mine in… a 3-liter toilet…
Dammit!!
50AnonymousSep 13, 2026 11:40
Wait, no aeration at all?
Yeah, they're gonna die
51AnonymousSep 13, 2026 11:41
Re: #50
Yeah, that's true
Especially at 3L
That's basically an unwinnable game
56AnonymousSep 13, 2026 11:45
At 3L with no filter, 2 Minami shrimp (a small freshwater shrimp) is about the max you could push it to
57AnonymousSep 13, 2026 11:46
Re: #56
For real
I'm already planning to move them to a 24L tank right now lmaooo
59AnonymousSep 13, 2026 11:50
But the Minami shrimp in my 45cm tank multiplied so much there's already over 100 of them
I've got filtration and aeration, but I just top it off with straight tap water and they're tough as nails
60AnonymousSep 13, 2026 11:51
Re: #59
That's probably just the filter and aeration making up for it
62AnonymousSep 13, 2026 11:52
Re: #60
It's just a bare-minimum hang-on-back filter though
64AnonymousSep 13, 2026 11:53
Re: #62
Wait, no plants either?
Then that's seriously tough
Yeah, I do think freshwater shrimp are hardier than medaka
63AnonymousSep 13, 2026 11:53
Why not just put them in a bigger container
66AnonymousSep 13, 2026 11:54
Re: #64
I only started with the bare minimum of plants, but they grew like crazy and turned into a jungle
I'm trimming and tossing them out about once every two weeks, that's how much they grow
67AnonymousSep 13, 2026 11:55
Re: #66
So you do have plants after all
Live plants grow at a ridiculous rate lmaooo
I get the impression mine turn into a jungle by day two already
Mine's anacharis though
70AnonymousSep 13, 2026 11:57
Re: #67
Anacharis grows well, but it doesn't do much for water quality…
Hornwort (matsumo) is better for improving water quality, I'd recommend that
72AnonymousSep 13, 2026 11:57
Re: #70
Hornwort, huh
That's going in the 24L tank too then
I'll pick some up next time lmaooo
73AnonymousSep 13, 2026 11:58
Re: #69
Just get a Suisaku or Rocaboy filter or something, doesn't matter which
Also throwing in some hornwort will change things a lot
78AnonymousSep 13, 2026 12:02
Re: #73
Nah, well, I'm graduating from this toilet tank anyway so it doesn't matter anymore
81AnonymousSep 13, 2026 12:04
Don't just wait for the cloudiness to go away, run a filter
Think about why rivers stay clear while puddles get cloudy
83AnonymousSep 13, 2026 12:04
Re: #81
Nah, this cloudiness is just dust from the substrate
It really does clear up if you wait
82AnonymousSep 13, 2026 12:04
There's around 20L in there
84AnonymousSep 13, 2026 12:05
Re: #82
No way there is
You think forty 500ml plastic bottles' worth of water fits in that thing?
85AnonymousSep 13, 2026 12:06
Re: #84
It does lmaooo
It's enough that two 8L buckets still don't fill it up
Guess it's hard to tell from the photo
86AnonymousSep 13, 2026 12:06
Why keep them in a bug-keeping plastic case like that?
Just buy an actual tank
89AnonymousSep 13, 2026 12:08
Re: #86
It doubles as both a bug case and a fish tank
Well, buying a glass tank would be best,
but it can't be helped

Background and Key Points of This Discussion

In fishkeeping, it’s often said that survival depends less on the raw volume of water than on whether filtration (bacteria breaking down harmful substances) is in place. In this case, the 3-liter tank had neither aeration nor a filter, so without any way to break down waste, water quality can deteriorate rapidly within just a few days. The thread was also split over how much water the tank actually held — the poster claimed it held close to 20 liters, but other commenters raised doubts by converting that to plastic-bottle equivalents. It was also pointed out that white cloud mountain minnows naturally swim in groups rather than alone, making it an easy misconception to assume that keeping “just one” of each fish would be fine simply because the fish count was low.

*This article is compiled and summarized from the 5ch (Newsspeed VIP) thread “Results of Putting One Medaka and One White Cloud Mountain Minnow into a Tiny 3-Liter Tank lmaooo“.

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