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Feedback on beginner 20 gal high stocking plan


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Hello all,

My son (6yo) has become really interested in keeping fish, so I've been researching a lot/watching youtube videos, etc.  I'm new to the hobby too, aside from the research I've done. 

I've purchased a 20 gallon high tank to go in his bedroom, and was hoping I could get some feedback on what I've tentatively come up with.  Already got a sponge filter and air pump.  I'm planning on having a co-worker run it in their tank for a few weeks to get some bacteria started in it so I can hopefully jump start my tank cycling.

First of all, this does not conform to the 1 inch per gallon rule... It is more congested than that, which has me a bit worried about it possibly requiring more periodic maintenance than desired.  I'm hoping to get away with water changes/etc once weekly or less once the tank is fully established.

I wanted the tank to be kind of exciting/interesting for my son, so I'm thinking a community fish tank with a "centerpiece" fish.

  • 6 x neon tetra
  • 6 x zebra danio
  • 1 x honey gourami (male)
  • 5 x pygmy corydora
  • 3 x amano shrimp
  • 2 x nerite snails

Does this sound reasonable, or should I take some things out to reduce the bioload?

I'm thinking about putting some plants in too, although I don't have those selected yet.

When looking at the different inhabitants required water parameters, I came up with using this spreadsheet I threw together.  The pH window seems kind of tight.  I'm not sure how hard it is to regulate pH.  Any insight you could provide on this would be helpful.  I haven't tested my tap water yet... I ordered some master test kits for that last week that haven't come in yet.

  Temp Min (F) Temp Max (F) KH Min KH Max pH Min pH Max
Water Parameters 72 77 6 8 7 7.5

Originally, I was thinking about getting silvertip tetras instead of the neon tetras and zebra danios due to their neat behavior where they will kind of swarm to your fingers when you put them on the glass, but I was deterred by what I was reading about possible nipping/aggressiveness.  

For substrate, I'm thinking about sand due to the corydoras.  I guess I would need to supplement that with root tabs when I start planting.

Thoughts and opinions are appreciated!

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I think that certainly sounds doable. It's certainly not as highly stocked as I've seen some people make theirs. Neon tetras and zebra danios are pretty easy fish when it comes to bioload. 

Especially if you have some live plants, I think you'd be okay. You may consider adding your fish slowly rather than all at once though. Make sure you are giving the bacteria time to adjust to the bioload.  Depending on the size of your sponge filter, if things aren't looking good you may need to add additional filtration. But that will depend on various other factors (how heavily planted it is, etc.).

Can't wait to see pics. 🙂

Edit: Also, I meant to add, I LOVE all the research and thought you've done before starting your tank. It's another reason I believe you'll be successful. You are clearly interested in doing what's best for your fish. 👍

Edited by MDoc
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I agree that this seems reasonable and with @MDoc's advice of adding fish slowly.  I'd pick one schooling fish to add after you cycle your tank.  Then maybe the corys, and then continue with a species at a time giving at least a couple weeks for your tank to "catch up" to each new addition, though you could probably do the shrimp/snails at the same time.  I'd personally probably add the gourami last--I know honey gouramis are supposed to be quite mellow, but it would help with any territorial aggression towards newcomers IF that existed.  

I know neons aren't rare or "fancy" fish, but I REALLY like mine in my 20 high with a betta, shrimp, and habrosus corys.  Since you're planning for a 6 year old--one of my 7 year old's very favorite things about our 20 high is that I got a glass lid and cheap NICREW aquarium light off amazon to replace the kit lid/lights and it has a blue night time mode.  The neons sort of fluoresce under it and look super cool when it gets dark! 

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I wouldn’t worry too much about pH and definitely would not try to adjust what comes out of your tap unless it’s extreme. Stability is much more important and you aren’t looking at anything that is terribly delicate.

Also know that if you do plants you will get snails. But you should do plants. Nerites may lay little white eggs if you get a female. They won’t hatch but some (including myself) don’t care for their appearance. Have you thought about a mystery snail. They get bigger and are more active.

have fun

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Thanks for all the feedback.  My plan was to put the zebra danios in after cycling first.  

Regarding the nerite snails... I was leaning towards nerites since I read somewhere they are supposed to be better at removing algae than the other snails, and don't breed in freshwater.

I guess if when I get to the step where I plan to add the snails/shrimp (just before the gourami), I don't have a lot of algae, I can re-evaluate.

Based on what I'm reading, Mystery snails need water hardness (12-18) and pH (7.6-8.4) that are higher than my range above, which seems like it could be an issue. 

I'm an engineer, so I tend to pay attention to the numbers... 

Do the other fish eat the nerite snail eggs, or does everyone just clean them off the glass themselves?

Edit: Our water is pretty hard here, although I have a weird citrus based water softener that I'm not sure how it will affect things.  I may end up having to use a different water source (or heavily condition the tap water) for my tank, which would be a pain.  Will see once I get those test strips.

Edited by Aldyrin
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I think this plan would work out just fine. As long as you have plenty of plants, it would be a great little ecosystem for your son to learn from.

My first suggestion is adding gravel to make things a bit easier. Like you said earlier, Corydoras species in general do well in both sand or gravel environments, but sand is preferred. I would do gravel where you want the plants, and sand where you don't need any plants, so that the catfish can root around as they please while also giving something easy for the plants to grow in. A good plan for this is gravel around the sides and back, and sand in the center/front of the aquarium. You can also sprinkle the sand over the gravel to provide some more sifting area for the catfish, while also promoting the growth of plants. Another side note, the pygmy cories do not dig so deep with their whiskers/barbels since they are so small, so only a thin layer of sand is actually necessary.

Another suggestion I have is with the stocking. Zebra danios are much faster, more active, and more boisterous than the other fish you chose for the aquarium. They might outcompete everyone else for food, especially the pygmy cories. If you really like the zebra danios, go ahead and keep them in the setup, as I'm sure they won't cause too much trouble. But here are some other options just in case you decide to go for something a little more peaceful:

  • Getting a small group of livebearers of some sort. They are very colorful and are fun to watch swim around, especially for a younger child. In addition, they will breed readily and easily in many aquariums, and that could be a fun experience for the whole family. You could trade in the babies for store credit at you LFS once they grow big enough to sell. Guppies, mollies, swordtails, endler's livebearers, and platies are all good examples of easy livebearers. I personally would go with endler's livebearers, as they stay pretty small and are the easiest types.
  • Peaceful tetras, rasboras, barbs, or even rainbowfish would work. You could add to your neon tetra school, or choose another species like the ember tetra, rummynose tetra, cherry barb, cardinal tetra, harlequin rasbora, and threadfin rainbow to name a few.
  • Add to your school of pygmy cories. I find that they are very shy if not in very large groups. I would add 5-10 more of them if possible. They are very fun to watch in these big groups, and will be a lot more outgoing and confident.

So those are my suggestions. Hope they help, and good luck! I look foreward to seeing your completed aquarium.

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So is the gravel easier to grow plants in than sand?  Is it just a weight/root retention thing?  I'm good with the idea (need to make sure to use non-sharp gravel, I guess). 

I was kind of on the fence about the zebra danios... I've seen them on "tank mates" lists for the other fish I have in the plan, but like you say, they are more active.  I thought a little excitement would be good for a kid tank...  I first looked at them since they are so hardy they are supposed to be good for beginners (like livebearers).

One of my co-workers said neon tetras just kind of hang around and can be kind of boring, so that was why I though the danios would be nice.  Is there a more middle-active option that you wouldn't be as concerned about outcompeting?  

I had looked at the endler's livebearers as another potential stocking option, but they seem to need way harder water (10-30 KH) than all the other fish on my list.  Maybe I'm putting too much stock in the numbers in these online care guides...

Would going with panda corys be better than pygmy corys considering compatibility with zebra danios?

If the pygmy corys are overly timid even in a group of 5, I might want to go with a different option... 

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So I measured my tap water parameters last night and they are going to change my stocking options since I don't want to have to deal with RO/DI water or chemically assisted water changes for our first tank.

I got the following:

  • pH: 6.8 to 6.9
  • dKH: ~12.5
  • dGH: ~16.5
  • Ammonia: 0 ppm
  • Nitrite: 0 ppm
  • Nitrate: ~2.5ppm

So most of the tetras, etc are out since they aren't meant for water this hard.

I did a little research and I'm thinking about something along these lines due to the harder water:

  • 6 x cherry barbs (1:2 male to female ratio)
  • 1 x platy (male)
  • 3 x endlers or fancy guppies (male)
  • 4 x panda corydoras (since they stick to the bottom unlike the pygmys)
  • 4 x cherry shrimp or 2 x amano shrimp
  • And a few snails maybe...

I went with males for the platys and endlers/guppies since I don't want to have to deal with a bunch of fry.  I'm a little worried about shrimp fry too, so I'm leaning more towards the amanos since they can't reproduce in fresh water.

The cherry barbs are supposed to be good for hard water. I've seen some posts saying they don't get along with guppies, but a lot of other posts saying they are fine...

Some of these fish are a little outside the preferred parameters for my water, but anecdotal forum posts I've seen seem to indicate it would be OK.

Thoughts on this alternate hard water setup would be appreciated.  Any obvious issues or beginner unfriendly?

Thanks in advance!


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