We've had a 5 gallon aquarium for years. Had white cloud mountain minnows and tetras. It had been empty for a few years when my daughter came home with a "free fish" from her science class. I believe it's one of those feeder fish - he looks like a skinny goldfish. Great - here it was in a plastic bag and no cycled tank to put him in! We got the tank set up, filled with dechlorinated water and hoped for the best. That was about 8 months ago and Diablo continues to live well and thrive. He's actually almost doubled in length.

I've been wanting a larger "community tank" forever. I love to watch schooling fish. So last weekend we bought a 1 year old 40 gallon tank off craigslist. What I didn't plan on is that it came with a 5" Tiger Oscar and three Giant Danios - a 1.5 incher, a 2 incher and the largest is about 3 inches. I have found a home for the Oscar (as awesome as he is, I know the tank is too small for him and he's far from being full grown).

The tank is tall - about 30" wide by 20" high by 12" deep. We left about 1/4 (10 gallons give or take) of the original water in there and filled to the top with dechlorinated water. The levels are fine so far, but I continue to test them. It came with two Top Fin 40 filters, which I someday hope to replace with a better filter. I kept the filter media in there (still looks clean enough) so the good bacteria can help stablilize the water. It also has a bubbler under the gravel. It has ugly black with neon gravel - I like a more natural-looking tank, but I haven't done anything with the gravel yet either. I hope to eventually add more realistic-looking plants and some aquarium-safe rocks and stones.

My questions:
- Will 3 more giant danios help complete that school? I've been reading they do better in groups of 6 or more. (And that'll hopefully eliminate the bigger one nipping at the smallest one.)
- What other kinds of schooling fish can I eventually add? I want to make sure everyone plays nicely. I notice that the Danios stick to the bottom 3rd of the tank for the most part (maybe they're just hiding from the Oscar, who ignores them), so I'm thinking a type that hangs out in the middle and another type at the top of the tank? I'm looking for people who've had Giant Danios with other types of fish and what they'd recommend.
- I have no experience with this - what is the bubbler for? Is it just for looks, or does it contribute to oxygenating the water?

Thanks in advance!

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- New-to-me 35 gal tank, slowly being updated & stocked
- 5 gallon hex tank, currently inhabited by my 12 yr old's "free fish" from science class - a feeder goldfish that's loving his new home, thriving and doubling in size in the last 6 months!

If those measurements are accurate... I think you have a 30 gallon tank. So 6 Giant Danios is pushing it.. I think they'll do well in a group of five. You'll be fully stocked with 5 Giant Danios in a 30 gallon tank.. If you want to add more, I suggest getting a filter that can filter a 60 gallon tank and adding live plants as well.

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Interesting - I just took the guy's word for it. I just measured it: 30"x22"x12".

If I'm fully stocked with the giant danios, I may be finding a home for them too. My wish and goal for this new tank was to have a couple schools of small fish.

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- New-to-me 35 gal tank, slowly being updated & stocked
- 5 gallon hex tank, currently inhabited by my 12 yr old's "free fish" from science class - a feeder goldfish that's loving his new home, thriving and doubling in size in the last 6 months!

Okay it's def a 35 gallon tank. With the gravel you'll probably have 33-34 gallons. That happens a lot on craigslist... sometimes they do it on purpose sometimes the people really don't know the size, since it's not a big difference, I'm guessing the latter. Now you know to double check just in case, ask them to measure it and take a picture with tape measure etc..

Here's quite a few schooling fish that you need at least 5 or more:

Panda Corys

Peppered Corys

Neon Tetra

Rummynose Tetra

Harlequin Rasbora

Zebra Danio

I think a nice set up would be

5 Corys
5 Tetras
5 Danios

You can add another small group of schoolers, or maybe get a couple centerpiece fish like Dwarf Gouramis or Honey/Honey Flame Gouramis.

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I have 7 neon tetras and 5 zebra danios in a 29g tank. I highly recommend
the neon tetras if you are looking for small schooling fish. They are
totally awesome to watch. Their colors are great and they are very peaceful.
My only complaint with the zebra danios is that they nip at each others tails.
They leave the other fish in the tank alone, which include the neon tetras, platies and serpae tetras but chase each other around endlessly. Funny to
watch. Good luck !

The Panda Corys are one of the smallest Corys, so they would be your best bet for having a Cory school.

I'd do: 5-6 Panda Corys, 6 Neon or Cardinal Tetras and 6 Harlequin Rasboras.

Or: 5-6 Panda Corys, either the Neons/Cards or Harleys and then a Honey Gourami.

Since Pigeon said you have a 35g tank, I can suggest what I've got in my 36g: 9 Harlequin Rasboras, 6 Three Line Corys (used to be 7), and 2 Angel fish (they need a 29g at the least.) I've got one Aqua Clear 70 filter (rated for 70g tanks) and an Aqueon 30 filter (rated for 45g tanks) so I've got way more filtration than needed, and the tank is heavily planted which also helps - also have an air stone for increased aeration.

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20g Heavily Planted http://www.aquariumforum.com/gallery...00&ppuser=8981
36g Bow Front Heavily Planted http://www.aquariumforum.com/gallery...00&ppuser=8981