20 gallon tall tank suggestions

Hello all. I had to rehome my Bleeding Hearts due to aggression issues. The tank was not big enough. Now I have 5 emerald corydoras and 2 nerite snails. I want my fish to be as happy as possible. 20 talls seem tricky to stock. I have very soft water and a ph of 7.

What are the tank dimensions (length x width x height)?

What is the GH in numbers?

Colin_T said:

What are the tank dimensions (length x width x height)?

What is the GH in numbers?

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Gh is 30. L is 24 in. W is 12. H is 16.

Danios, cherry barbs, Rasboros, and some bottom dwellers such as some loaches or cories are usually peaceful fish that could live happily alongside Bleeding Heart tetras. Try to avoid placing less active species, like dwarf cichlids, as a tetras fast movements can cause them a lot of stress.

Here is an example tank


My tank for rescued danios and tetras. It is a 60 gallon

Moony42 said:

Danios, cherry barbs, Rasboros, and some bottom dwellers such as some loaches or cories are usually peaceful fish that could live happily alongside Bleeding Heart tetras. Try to avoid placing less active species, like dwarf cichlids, as a tetras fast movements can cause them a lot of stress.

Here is an example tank
View attachment 92612

My tank for rescued danios and tetras. It is a 60 gallon

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Oh no, I had to rehome my bht. Now I have 5 corydoras.

is the GH 30ppm or 30 dGH?

If it's 30ppm and you want something different, perhaps splashing tetras or some Aphyosemion or Nothobranchius killifish. Maybe some Licorice or Sparkling gouramis. If you can find Pseudomugil gertrudae or Iriatherina werneri, they would be ok in that tank.

Colin_T said:

is the GH 30ppm or 30 dGH?

If it's 30ppm and you want something different, perhaps splashing tetras or some Aphyosemion or Nothobranchius killifish. Maybe some Licorice or Sparkling gouramis. If you can find Pseudomugil gertrudae or Iriatherina werneri, they would be ok in that tank.

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It is ppm. Sorry.

Cory catfish have no problems sharing a tank with small, active schooling fish. Tetras, like the neon, cardinal and serpae tetras fit this bill. Additionally, livebearers like the guppy also will get along well with corys.

the GH is too low for livebearers.

Soft water species are what you should be looking at, agree. Forget any livebearers.

Most but certainly not all of the common tetras can work, same for the rasboras. In both cases fish that do not get much over an inche (3 cm) in length. Danios are too active for this small a tank, so I would forget those.

Serpae Tetras were suggested, no, these will not work here. This is a feisty fish prone to nip fins, and it must be in a group of at least 10-12, and this requires a 30g tank (30 inch length) minimum, just for the Serpae Tetras.

Most fish species tend to remain at a specific level in the water column. Cories obviously are primarily substrate-level fish as they are down on the substrate most of the time. Fish such as the quiet tetras are often mid/lower level fish. Many rasboras are mid to upper level. Hatchetfish are upper level, at the surface. Pencilfish depending upon the species can be primarily upper/surface, or mid-tank.

Some species in each of these groups are well suited to a standard (high) 20g. I have one of these in my fish room. With your soft water, the difficulty will be not finding suitable fish but finding too many!

Knowing what you like will allow me to suggest some specific species. Floating plants, meaning substantial ones like Water Sprite, Frogbit, Water Lettuce, or a stem plant left floating like Pennywort, will be essential here as all of the species suited to this tank and water are not fond of overhead light.

I do like the pencil fish and the rasboras. Hatchets are cool,I just don't want to change my filter set up or cover up the holes they could jump through. I'd like to keep them someday though. I love the red in some of the pencil fish. The Rasboras are really pretty too. I ordered frogbit a few days ago.

Ch0le said:

I do like the pencil fish and the rasboras. Hatchets are cool,I just don't want to change my filter set up or cover up the holea they could jump through. I'd like to keep them someday though. I love the red in some of the pencil fish. The Rasboras are really pretty too.

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For surface fish, the rocket pencilfish as it seems to be commonly called, Nannostomus eques, is ideal. I have had a group of a dozen or so for many years (so long I have replaced the originals that died of old age with younger fish to maintain the group), and they remain together almost continually, close to the surface, among floating plants. This is not a brightly coloured species, but it is one of the more peaceful (male squabbles are interesting and in my experience never lead to anything serious) of the pencils, swims at an oblique angle, and as I say at or very close to the surface. Mine spawn regularly, though the tiny eggs deposited on the undersides of leaves get eaten before they hatch, except once or twice. Photo below (not my fish, just a good photo of the species). A group of 10-12 would be fine in a 20g with floating plants.

Among the red-hued pencils, none is more beautiful than the coral red, Nannostomus mortenthaleri (photo below). This species is another very peaceful one, and when I had them (they are very rare here, only saw them once many years ago now) they separated out (unlike the above) and seems to swim just about everywhere in the middle 2/3 of the tank. They need lots of plants or branches in the mid-tank region. A group of at least six, up to maybe eight. Another red newer discovery is N. rubrocaudatus, but the red is not quite as extensive as on N. mortenthaleri. Rarely seen, I had a group about nine years ago but have not seen them since locally. These fish are obviously all wild caught, and expensive for import, so there is not as wide a market for them.

The dwarf pencilfish, Nannostomus marginatus, is another peaceful shoaling pencil. This species has quite a large range over parts of the Peruvian, Brazilian and Guyanan regions, and there are subtle differences in the geographically-isolated populations. This fish swims the same as the coral red, spread out and over the middle 2/3 region. A group of 8-9 minimum.

Considering the 20g tank, with the cories, you could have the group of N. eques and a group of one of the others.
Inj one of the photos there is a cardinal tetra in the background, and this is a species suited to the same environmental conditions. But given its size, the smaller false or green neon, Paracheirodon simulans, in a group of 9-10 would be a nice addition with the two pencilfish groups and cories. This species tends to remain in the lower half. It is very closely related to the cardinal, differing in its DNA by only a few chromosomes.

Thank you for all of your responses. I can't come here without learning something new. I have a lot to digest. Thank you for the great pics and info. It is much appreciated. Also, id I decide on some rasboras as well,how many should I get?

Don't think you can go wrong with pencilfish but I agree that Serpae tetras are best avoided. I had some that I ended up taking back because they were (IMO) little terrorists.

@Byron is there an easy way of differentiating n.marginatus from n.trifasciatus? Mine were sold as the latter but looking at the pics its hard to tell. Mine have red in the dorsal and pelvic fins (which are very small) and no red in the anal (also very small) or caudal fins. There is also no red on their bodies.

seangee said:

Don't think you can go wrong with pencilfish but I agree that Serpae tetras are best avoided. I had some that I ended up taking back because they were (IMO) little terrorists.

@Byron is there an easy way of differentiating n.marginatus from n.trifasciatus? Mine were sold as the latter but looking at the pics its hard to tell. Mine have red in the dorsal and pelvic fins (which are very small) and no red in the anal (also very small) or caudal fins. There is also no red on their bodies.

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I have N. trifasciatus presently, and have had N. marginatus but they grew old and died out after I guess some seven or eight years. I'll paste some excerpts from my profiles on these two species that may answer your question.

The species Nannostomus marginatus is a widespread polymorphic one [meaning that there are varying colour morphs or variants distinctive to geographic areas], with distinct populations occurring in the Guyanas and in several widely-separated areas in the Amazon basin (Weitzman, 1966). At least three distinct colour variants are known. The original description by C.H. Eigenmann in 1909 used specimens collected in Maduni Creek, Guyana. The populations from the lower and upper Amazon basins may prove to be sufficiently different after further study to merit subspecific recognition (Weitzman, 1966). When first discovered, the beautiful coral red dwarf pencilfish [now a distinct species, Nannostomus mortenthaleri] was originally described as a subspecies of N. marginatus. This species (N. marginatus) does not possess an adipose fin.

The species Nannostomus trifasciatus is also a widespread polymorphic one. Over time, some of these were described as new species (Poecilobrycon erythrurus and Poecilobrycon vittatus are two) that are currently considered conspecific so these taxonomic names are synonymous. This species does possess an adipose fin.

Photos attached are N. marginatus Guyana form, N. marginatus Peruvian form, N.marginatus from Rio Ampiyacu in Peru. Last photo is a form of N. trifasciatus. None of these are mine, they are from the internet though reliable sites.