General 20 gallon tank questions

[mdingrimsby]

Hi guys,
I am new to the forum and this is my first time running an aquarium on my own. When I was younger my Dad and I had one together. I have a few questions for you! But first, a summary of my tank conditions.

I have set up and cycled a 20 gallon (tall, not wide). I just put in two male guppies and one male, one female swordtail. The PH is 7. General hardness is 60. Temperature is 78. I have no live plants. I want it to be a community tank. I have one top fin 20 gallon power filter.

I did not want to over do it and add a bunch of fish at once. Here are my questions:

1. From what I have read I will need to add at least one more female swordtail to keep the aggressiveness of the male in check. Is this correct?

2. In 2-3 weeks I would like to add Neon Tetras. I was thinking I would add 3, and then add another 3 more two weeks later. My local pet store said that I could still add 6 at once and it wouldn't overload the tank. He also mentioned that adding just three might stress them out. What do you think? Is a temperature of 78 too high for them? Also, I have read that they are been over bred - are there particular things to look out for when buying Neon's, any specific physical signs?

3. Live plants. I have never used live plants. I am considering adding them. When adding them should I be aware of anything? Do I need to do a water change when adding them? How do they affect my water levels and waste? Is keeping plastic plants just as useful when it comes to hiding places etc?

4. After adding the 6 neon's and I presume one more swordtail, do you think there will be room for a couple more fish? I was considering adding either a couple more male guppies or 3-6 Harlequins. The Harlequins stay reasonably small, but would 6 be overstocking?

5. If I skipped the Harlequins and went for some bottom feeders would that be better? What bottom feeders would you recommend? I would like some playful or colourful ones.

So overall my tank would be:

1. Two (or four) male guppies
2. One male and two female swordtails
3. Six neon Tetras
4 6 Harlequins (Or 0 depending on whether I do the guppies.)

Thanks in advance, I appreciate the time it takes to answer these questions thoughtfully.

 

[Colin_T]

Hi and welcome to the forum

You mention that your general hardness (GH) is 60. If that is 60ppm then that is very soft and the guppies and swordtails will probably have problems. Livebearers like guppies, mollies, swordtails and platies need water with a GH above 200ppm and a pH above 7.0. your pH is fine but 60ppm of GH is way too low for them to be happy in the long run.

If you can confirm the general hardness is only 60ppm that would help. If it is only 60ppm then I would not get any more livebearers.

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Livebearers should be kept in groups of males or females. If you want to keep a male then you should have at least 6 females per male. With swordtails, if you have a group of females and no males, the dominant female can change sex and become a male. However, check the GH before getting anymore swordtails or guppies.

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If you get neon tetras, they will be fine in soft water with a GH of 60ppm and you should buy them all at once. Try to get 10 of them as well. If the tank has cycled then adding 10 neons will be fine.
Drop the temperature down to 76F.

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When you buy neon tetras or any other fish, do not buy any fish from any aquarium if there is a dead fish in the tank. Go back a week later and get them then.

With neon tetras, look at the blue line on the body, every neon tetra in the tank should have a nice solid blue line that runs the full length of the body and there should be no gaps in the blue line and no white patches on the blue or red lines. Some neons have a straight blue line and others will have a slight kink in the blue line about half way along, this is normal. The males have a straight blue line, the females have a kink in the blue line.

Check their fins and all the fins including the tail should be open and stand out away from the body. Do not buy fish if their fins are clamped up or stuck close to their body.

Look for any white spots on the body or fins. Do not buy any fish from an aquarium if a fish has white spots on their body or fins.

Look for white, cream or grey patches on the body or fins. Do not buy any fish from a tank with fish that have that.

Do not buy any fish from a tank if any of the fish in the tank are rubbing against objects in the tank.

Look at their mouth and it should look normal. If any fish in the tank has red or white lips, do not get any fish from that tank.

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If you have a light unit on the top of the aquarium, then you can try live plants. Some good plants to try include: Ambulia, Elodia/ Hydrilla, Hygrophila polysperma, Ludwigia, common Amazon Sword plant, narrow Vallis, Water Sprite (Ceratopteris thalictroides). Water Sprite can float or be planted in the gravel. The other plants should all be planted in the gravel.

When you get plants try to buy them in pots because they usually have a better root system. When you get them home, look at the leaves and stems and remove any snails or jelly blobs on them. The jelly blobs are snail eggs.

Once you have checked them for snails, carefully remove the pot and rinse the roots in a bucket of water. Then put the plant in the tank and move some gravel aside, put the roots and bottom bit of the plant in the depression and cover with gravel. Most potted plants have several plants per pot and you can divide them up and spread them out a bit.

Live plants will need the tank light on for about 10-12 hours per day. if you get lots of algae then reduce the lighting period by a couple of hours and see how it goes.

Plastic plants do the same job as live plants when it comes to providing shelter and protection for the fish.

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I am unsure what the tank dimensions are. In Australia we sell aquariums in feet not gallons. If you can provide us with the tank dimensions (length x width x height), then we can offer more advice about other fishes that can go in your tank.

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Bottom feeders will depend on tank dimensions and could include Corydoras or Khuli loaches.

 

[Byron]

I agree, if you have soft water then take the livebearers back immediately. Aside from that, this tank is not sufficient space for a swordtail. But it won't live long in soft water anyway.

I also agree about the neon tetra. Always add the entire group of a shoaling species, they will settle in faster and with less stress. And a lower temperature, around 75 F would be good. Neons do not like warmer water. And for substrate fish, like cories, the lower temperature is best.

The tank dimensions will be 24 inches length by 12 inches width (front to back), and 15 inches height, as this is a standard 20g high. Before suggesting plants, I would want to know more of the light over the tank.

 

[mdingrimsby]

Thanks for the wonderful feedback. I will double check my water hardness. I know that my area in general has hard water, so I may have read that wrong.

In response to the dimensions of the tank it is 24 long, 12 wide and 19 high.

Might I ask why this is too small for swordtails? I have no problem taking them back if I need to.

I have LED lights above the tank.

 

[Essjay]

The reason the tank is too small for swordtails is because they are big fish. Females can grow as large as 6 inches/15 cm. They need a tank with a footprint of at least 48 x 12 inches (120 x 30 cm)

I will double check my water hardness. I know that my area in general has hard water, so I may have read that wrong.

Please do double check. The 60 you gave, if ppm, is soft so the advice on fish the others gave is based on your having soft water. If it turns out you have hard water, you can't keep soft water fish. There are half a dozen different units used for water hardness, which is why we always ask for the unit as well as the number.

 

[mdingrimsby]

The reason the tank is too small for swordtails is because they are big fish. Females can grow as large as 6 inches/15 cm. They need a tank with a footprint of at least 48 x 12 inches (120 x 30 cm)



Please do double check. The 60 you gave, if ppm, is soft so the advice on fish the others gave is based on your having soft water. If it turns out you have hard water, you can't keep soft water fish. There are half a dozen different units used for water hardness, which is why we always ask for the unit as well as the number.

The swordtails response makes perfect sense. I had read they grew to four inches, which I thought might be okay. I will definitely take them back. As for the water, I am going to take a sample to my LFS and have them talk me through their readings so I can take better readings in future. Will post more when I have done so later today.

 

[Colin_T]

When you go to the pet shop to have the water tested, write down the results in numbers when they do the test.

I have never seen a swordtail that is more than 4 inches long (body size not including tail), but wild caught swordtails can get bigger than 4 inches. Most of the stuff in the shop is inbred and hybridised with platies, and are unlikely to get more than 4 inches for females and 3 inches for males.

However, even at that size it will be a struggle in a 2ft long tank and if the GH is only 60ppm then that's a bigger issue again.

 

[Byron]

The other thing about tank size that has not been mentioned involves the activity level of the species. A four or five inch fish that is an active swimmer like swordtails are will be very cramped in a tank with a length less than 36 inches (90 cm).

And it is a case of much more than just "exercise" space as we might think. Space around a fish impacts it physiology, metabolism, stress level, immune system...all interconnected. Chemicals are released by fish into the water and these are read by their own species (pheromones) and other species (allomones) and these impact the afore-mentioned.

 

[mdingrimsby]

The other thing about tank size that has not been mentioned involves the activity level of the species. A four or five inch fish that is an active swimmer like swordtails are will be very cramped in a tank with a length less than 36 inches (90 cm).

And it is a case of much more than just "exercise" space as we might think. Space around a fish impacts it physiology, metabolism, stress level, immune system...all interconnected. Chemicals are released by fish into the water and these are read by their own species (pheromones) and other species (allomones) and these impact the afore-mentioned.

Thanks again for the information. There is obviously something wrong with the way I have been measuring my tank, as the pet stores were more what I expected.

Water General Hardness is 150ppm.
PH is 7.8

So with that in mind, how does it impact my original questions - anticipating that I will remove the Swordtails? Thanks for your patience with a new beginner

 

[Colin_T]

general hardness at 150ppm is soft water and not really suited to livebearers. However, tetras, rasboras, cories and small gouramis will be fine.

 

[mdingrimsby]

general hardness at 150ppm is soft water and not really suited to livebearers. However, tetras, rasboras, cories and small gouramis will be fine.

Do you think I should also take the guppies back then, or will they be okay?

 

[Byron]

Thanks again for the information. There is obviously something wrong with the way I have been measuring my tank, as the pet stores were more what I expected.

I don't follow this, sorry. Your measurements of the tank in post #4 are a 20 gallon high tank. Nothing wrong there, but it is not long enough for swordtails, that's all.

Water General Hardness is 150ppm.
PH is 7.8

I agree with Colin that this is too soft for livebearers; guppies might manage, but not plates, mollies or swordtails even if a larger tank. You might as well return the guppies, as it means less fish load so you can do the others better. There are many soft water species that will do well. Your earlier numbers indicate a lower pH and GH, and the pH may lower naturally in the aquarium depending upon the KH (carbonate hardness or Alkalinity) which is usually tied to the GH. This will be even better if the pH does lower, but it is not something I would worry about.

Neon tetras will be fine, and Harlequin Rasboras will be fine, as far as GH and pH are concerned. Both are fairly sedate fish, meaning they are not active swimmers, so the tank size is not an issue for a group of either. And a group of cories. You want decent numbers though, whichever. A group of 7-9 or 10 cories (the medium-sized species), and a group of 9-10 neon tetra? Or a group of 7-8 Harlequin Rasbora (with the cories)?

 

[AbbeysDad]

I've come to challenge a lot of these 'old school rules' of fishkeeping
(not to mention a lot of the myths that are repeated over and over:
> 1" per gallon
> 4x-10x filter flow rate
> over filtration
> more filtration = more fish
> ......).
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I think a pair or trio of Swordtails can live just fine in a 20g tank (and I'm likely the only one here growing out 100-200 Swordtails!)
Now my water is neither hard, nor soft really with a pH of 7.6, but I've had Angels, Neon Tetras, Cories, Swordtails, and Mollies all in the same planted tank living just fine.
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Many/most of the fish we have in the hobby have been bred and raised in a wide range of water parameters. Will some fish do better in soft, acidic water and others do better in hard, alkaline water? Perhaps, especially any wild caught fish, but I feel that sometimes we can get too caught up in a rigid mindset that just doesn't make sense. I have bred and grown out Angels to adults in my water...does it really make sense then to think these fish can only live in soft, acidic water?
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Water just way to soft or liquid rock - so you fix it with Equalibrium or cutting with RO or distilled water with each water change - where there's a will, there's a way.
I have high nitrates in my well water....so I pre-filter through API Nitra-Zorb to remove it.
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As to water quality it comes down to bio-load and water change frequency/volume. A well maintained 10g tank can potentially have better water quality than an average 100g tank.
I shake my head when I see posts of hobbyists that have larger (medium to heavily stocked) tanks with canister filters that they only service every 2-3 months or so and only do limited partial water changes once or twice a month!!! Water may look 'clear', when in fact it's very polluted!

 

[Colin_T]

Yes a trio of captive bred swordtails can live in a 20 gallon (2ft long) tank. However, the water is on the soft side and the OP wants neons. Mixing swordtails with neons in soft water, might be ok, but it might not end well. Personally I would keep neons and swordtails separately and increase the hardness a bit for the swordtails.

If the OP can find locally bred swordtails, then that's fine and they could keep them in the soft water. But again swordtails and neons, possibly not the best mix. Platies and neons (assuming water chemistry was suited to both species), would be a better mix because platies are smaller and less of an issue to neons.

I am unsure whether the shops there buffer their water at all. But in every shop I have worked in, we had tanks for livebearers and tanks for tetras, and the livebearer tanks had minerals added to them after every water change. We had to do this because the water here is very soft (GH less than 50ppm) and the livebearers simply fell apart in the tanks if they didn't have mineral salts added to the tanks. We buffered the Rift Lake cichlid tanks too.

If the OP wants to raise the GH up to 200ppm, then guppies and platies could be kept with neons, but the neons would be borderline due to the harder water. And does the OP want to buffer the water?

One option would be to get another tank and put them both on a double tier stand. Then they could keep neons in one tank and buff the other tanks for livebearers

 

[Byron]

When a member who has, or may likely have, less experience posts asking for direction, I see no value in agreeing with what "might" work. That weakens the forum, and provides less than reliable assistance/advice. The chances are something will go wrong, the fish being weakened will succumb to something, and likely begin dying, and the member may give up. When someone asks for help or advice, I for one will continue to give the best I can. Anything less is not fair to the member, nor to the forum.

Swordtails will not be in good health in a 20 gallon with water as soft as that here. Yes, they may live, but at what cost? Just because we can't pet or talk to a fish does not mean we should not be just as concerned for its well being. Also, experienced members are better able to discern things, so it is probably easier for them to rectify this or that. New hobbyists do not have this advantage, so they should be correctly steered down the best path for the good of their fish.