20 gallon tank stocking question

[fishlover111]

Hi guys, I have had my 20 gallon tank for a while now. It has been running smoothly and I just wanted to ask if my aquarium is decently stocked or if it is overstocked. I have 6 zebra danios, 5 cory catfish, 3 male guppies (they are not aggressive towards each other and I don’t want females to give birth), and a dwarf gourami. I am not entirely sticking to the one inch per gallon rule I’m just doing what works best for me and I have been maintaining the tank.

 

[libertybelle]

Looks pretty good to me.

The actual best stocking for your tank will depend on a lot of factors such as

filtration
fish temperament (any bullying / bickering)
tank layout (lines of sight broken up, places to explore)
is it planted and with what (heavy planting adds hiding places and fast growing plants suck up nitrates etc)
how large of water changes do you want to do and how much wiggle room do you want to have in case of something going wrong (power outage/filter break down).

For example I used to stock lightly because where I lived we’d have a couple power outages a year and oxygenation and filtration drop when the power is out, obviously. Being understocked meant the tanks could be without power for quite some time before the fish would suffer ill effects. Now where I live I have a generator and the tank is planted with so many plants that I never see nitrates build up between water changes because the plants use them all up. I could stock much heavier without problems.

If lots of those elements are in your favor (plenty of filtration, lots of hiding spaces, fast growing plants etc) you could probably add a bit. If not you’re probably good where you are! If you do decide to add fish I would stick with enlarging your schools rather than adding any new types of fish. Danios and especially cories like to be in big groups and schooling fish often exhibit their best behavior in larger than the minimum groups!

 

[fishlover111]

Yes those are all in my favor! All my fish are peaceful, I have 2, 20 gallon filters that seem to work great. I do large water changes as required and everything is good! I also have a lot of artificial plants seeing as I have no luck with live plants and a submarine ornament. I am looking to add in a couple more fish so thanks for the advice. My cory catfish have been acting weird recently and are hiding and dart around the tank when they see me, they look very afraid of me. Should I add more cories? If so about how many more? How many danios do you think I should add as well? They seem to be very happy right now so I’ll either add more danios or get another type or fish. Do you have any recommendations of what I should do?

 

[libertybelle]

You don’t have that much room for new fish so anything schooling probably wouldn’t be a great idea. You barely have room to get to the minimum recommended school size and almost all schooling fish would be much happier in a bigger school. Many of them will just hide if there aren’t enough, which makes for a boring tank! I also personally like the look of big groups of just a few species in my tanks, rather than a melting pot. I have about 20 rummy nose tetras in my 55 and the big school moving around together is stunning.

If it was me personally I would add another 3-5 cories of the same type you currently have. (Some people think they can mix and match but cories school with their own species and they do so much better in big groups. They just hide all the time if they’re not comfortable.) What kind of Cory do you have. Some of them get bigger than others.

I’d also probably add inverts. Nerite snails and shrimp are my favorite. Before my glo tetras/barbs got big enough to eat shrimp I went out and got a couple dozen ghost shrimp for my 55! They’re short lived but inexpensive and add a ton of fun activity to the tank. Sadly I can’t have shrimp in there anymore because the fish got bigger and learned ghost shrimp are delicious.

You could also consider adding a few glofish danios. They’re the same species and will school with your zebra danios but can add a cool pop of color. (Just make sure you get the danios, the other species (tetras /barbs / sharks) are all different species and you don’t have room for a school of them.

 

[fishlover111]

I have emerald green cory cats. Would getting 3 more be fine so there are 8 of them? Then for the zebra danio I can also add three more, (the glo fish idea sounds great!)so there are 9. In total I would have 8 cories, 9 danios, 3 guppies, and 1 dwarf gourami. Would this work? If this works how many ghost shrimp would you recommend?

 

[libertybelle]

You could probably do a few of both yes. Just make sure you don’t add too many fish at once and watch your nitrates. If they start going higher then stop adding fish or add more water changes to compensate. Ghost shrimp have a very low bio load. You could toss a dozen or more in and it would have very little effect on the bio load. They’re great little scavengers and as a bonus to just being fun to watch, they will scour the tank for missed fish food and help keep everything clean.

The ghost shrimp come with a caveat though. They are usually sold as feeders and they are unfortunately treated like feeders. They’re packed in tight and just generally not treated with much care in shipping. It’s pretty normal to lose a few anytime you add them to your tank.

Do you quarantine new fish before you add them? It’s a very good idea if you don’t already and the shrimp should ideally be quarantined too. Live shrimp don’t add much to the bio load.... a couple dead ones unnoticed in the tank... that could cause problems! Better to let them settle in in a quarantine tank so you don’t risk your main tank.

 

[fishlover111]

I just added the 4 new danios and dwarf gourami this week so I will be waiting for the nitrogen cycle to complete before adding anything else. I am going to the store later to replace one of the danios because it was sick when I bought it and it died in a day. I checked my water and everything was fine. Can I get about 10 shrimp today and add them or should I wait? Yes I do have a quarantine tank, it is about 5 gallons. I also have a breeder net I can put them in that way I can see the dead ones easier.

 

[Barliman]

Hi guys, I have had my 20 gallon tank for a while now. It has been running smoothly and I just wanted to ask if my aquarium is decently stocked or if it is overstocked. I have 6 zebra danios, 5 cory catfish, 3 male guppies (they are not aggressive towards each other and I don’t want females to give birth), and a dwarf gourami. I am not entirely sticking to the one inch per gallon rule I’m just doing what works best for me and I have been maintaining the tank.

Sounds like a nice stocking level to me. I might add a couple more corys and 2-3 nerite snails , but you're not overstocked at all. As for the "1 inch per gallon" rule, ignore it. There are so many variables that determine how many fish you can keep in a tank that it's worthless.

 

[fishlover111]

Thank you! I plan on adding 3 more cories because they are hiding right now. I am planning on getting ghost shrimp as well. May I ask if there are any benefits on having snails?

 

[Barliman]

Thank you! I plan on adding 3 more cories because they are hiding right now. I am planning on getting ghost shrimp as well. May I ask if there are any benefits on having snails?

Snails can be good scavengers and help with controlling some types of algae. Nerites in particular have a good reputation for that, plus they can't successfully breed in freshwater, so you won't be overrun with them (unlike with many other snail species). Just remember they'll need a regular food source, too. You shouldn't make them rely on just scavenging.

 

[fishlover111]

Earlier I said I Have two filters and I recently added the second one today. My tank water looks cloudy and it’s never don’t this except for when I first started out. This is normal right?

 

[libertybelle]

I would not add anything while the water is cloudy. That can be an indication of a bacterial bloom. Normal in the sense that it is a normal part of cycling but still a warning sign that you should check your parameters again to make sure you’re not having an ammonia / nitrite spike. Most stores will give you a store credit in lieu of replacement fish so you can come back for fish when the tank is ready.

The net will let you see bodies but won’t protect your other fish from any potential parasites or illnesses brought home in the fish or water from the store. Ideally anything that goes into your tank should spend a couple weeks in quarantine first to make sure they didn’t bring anything bad with them. That includes any replacement fish.

Are all the fish in this tank new? If so in that case I would not worry about (once the cloudiness clears up) adding a few more if they are from the same source and you haven’t seen any ammonia or nitrite. In that case they are all essentially in quarantine, you wouldn’t have any ‘known to be healthy’ fish to protect.

 

[fishlover111]

Yea I’m not going to add new fish until it clears up. I only had the 4 danios and dwarf gourami that are new (3 or so days). I am going to check my water later today.