Help choosing tank mates

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Andrew waterson

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Hi All,

I'm just about to embark on my 1st tropical fish tank setup
Will be starting a fishless cycle in the next few days, so hopefully adding fish in the next 6 weeks or so

I'm planning on a community tank, I have a 160 litre tank, sticking within the 1cm per litre an fish max size of 15cm.
It will be moderately planted

My water is hard alkaline (London!) with the following stats from the tap (from testing and backed up by my post code water report)
PH: 7.6-7.8
Ammonia: 0
Nitrite: 0
Nitrate: 30ppm
Hardness: CaCO3 268ppm, Degrees Clarke 19, Degrees German 15

The below is my current list and predominately based on water requirements and internet research!
6 mollies (small variety like neon orange)
6 swordtails
4 rainbow fish (smaller variety probably Bosemani)
1 Blue Gourami
1 Indonesian Flying Fox

This should be under 160cm with them all at full\max size (I know the live breeders may impact this in the future!)

The all are listed as liking PH up to 8 and have 26 degrees C as an ideal temp

Would they make good tank mates
From my reading the main ones sticking out at the mollies and Gourami, its sounds like the sometimes bully each other
 
Not sure where you got info about gouramis being ok in alkaline water because they normally occur in soft acid water. They will tolerate a pH between 7.0 & 7.8 but I wouldn't take them over 8.0.

Mollies shouldn't bully the gourami but male blue, gold, opaline & 3 spot gouramis (same fish different colour) are pretty obnoxious when they mature and might cause issues to male mollies. Having said that, if you only have one adult male rainbowfish they can spar with the big mal gourami.

Melanotaenia boesemani are a big rainbowfish and reach 4 inches in length.
 
The Gourami is a Trichopodus trichopterus
According to the seriously fish DB is PH is 5.5-8.5 (I've been told this site is a good one)

But sounds like they aren't very friendly so think I'll give them a miss!

For the rainbows (11cm for males) is the tank a bit to short, it's 1m

I'm keen to get a bit of variety in shape and behavior (mollies and swordtails being close ish relatives), but struggling to find many options with these water conditions
 
I'm also considering 3 Betta (1 male) instead of the rainbows.
But iveI seen that the Mollie's and swordtails may be prone to nipping their fins.

Are they a better option?
 
I'm also considering 3 Betta (1 male) instead of the rainbows.
But iveI seen that the Mollie's and swordtails may be prone to nipping their fins.

Are they a better option?
No! They are not suitable for a community tank.

In case a second opinion is needed - No! Your water is too hard.
 
I thought so!

On the water hardness, is the seriously fish site reliable and accurate?
I checked a few of the betta varieties and the all had much high hardness ratings (some up to 360+ ppm)

If is not very reliable I think I might be a bit stuck!!
 
Blue gouramis are probably more tolerant of hard water but labyrinths (gouramis and Bettas) all naturally occur in soft water.

If you get a female blue gourami, there won't be any agro issues.

If the tank is 1 meter long it is fine for any of the rainbowfish.

If you want a small roundish blue rainbowfish then Melanotaenia praecox is the fish to look at. You could have 8-10 of them in the tank and their colour is pretty fancy when they mature. They are also small enough not to cause any issues to the mollies or swordtails.

You do not want to put a Betta in with rainbowfish, it doesn't work :)
 
Last edited:
The Betta is definitely out!!

I really liked to look of the dwarf rainbows, but is my water a bit too alkaline at 7.8?

All the advice is greatly appreciated!
 
Seriously Fish is just about the best, most accurate website out there.

pH is not as important as hardness. You need to make sure any fish you get has your hardness somewhere in its preferred range, preferably near the middle of the range.
Some fish profiles give hardness in ppm - that's the same as mg/l CaCO3, so yours is 268 ppm. Other profiles give the hardness in dH, which is the same as German degrees, so yours is 15 dH
 
Thanks, I'll go and check them out and add the info to my research list!

I've got the pH and temperature for them, but a lot of the online shops sites (all pond solutions... Etc) don't list the hardness, so I didn't know it was as important.

Out of interest where does the temp range sit in the equation Vs hardness and pH (I.e is it more important than ph?)?
Most of my list is in the 24-26, but there are a few at 26+
Would they all do ok with 25.5-26, or is it best to stay in the middle of the range?
 
Personally I would try to aim for species that all like the same temperature. If, say, one species liked 23 to 26 and another 22 to 25, there is plenty overlap. I would not keep fish that liked 24 to 26 with fish that liked 26+. You would need to decide which fish you really really want then choose tank mates based on their needs.

pH is important, though fish are OK in pH slightly outside their quoted range as long as hardness is within their range.
 
All rainbowfishes except wild caught Iriatherina werneri, Rhadinocentrus ornatus and some of the Pseudomugils will do better in hard alkaline water compared to soft acid water. So your water will be fine for any rainbowfish that has been captive bred, which is pretty much all of them :)
 
Thanks all.
Going to do a bit more research on all the parameters and make up a list from the local aquarium stores as well

I think the Mollie's, swordtails and rainbows of some description are a definite. But will rethink the others

I've prob got over a month of cycling before I start buying, so can plan it out a bit more

I'm thinking of adding the Mollie's and swordtails 1st and giving it a few weeks to make sure the tank conditions stick to good safe levels

Does anyone have a experience buying fish online? ... The idea of getting fish in the post is worrying, but it will mean I have more options
 
I agree with posts to date, but have a few comments on some issues.

Plants and cycling...you mention live plants so I would not cycle. Adding ammonia with plants can backfire. I explained plant "cycling" yesterday in post #26 in this thread:
http://www.fishforums.net/posts/3796934/

I think the Mollie's, swordtails and rainbows of some description are a definite. But will rethink the others

This aquarium is not sufficient for all of these. Swordtails get 5-6 inches and need minimum 120 cm (4 feet) length, so I would give those a miss. The mollies will be OK, and the rainbows in a group but the species is not decided and this might make a difference. I assume the other fish mentioned in post #1 have been eliminated from consideration.

Out of interest where does the temp range sit in the equation Vs hardness and pH (I.e is it more important than ph?)?
Most of my list is in the 24-26, but there are a few at 26+
Would they all do ok with 25.5-26, or is it best to stay in the middle of the range?

Each of these parameters (GH, pH, temperature) affect fish in different ways, so all are equally important. GH is the level of dissolved mineral (calcium and magnesium primarily) in the water and this has a significant effect on fish. Fish from harder waters need these minerals to be taken into their bloodstream, while fish from softer waters do not and have varying degrees of tolerance. The pH is less critical, provided it is within reason and not extreme either way; its effect on fish physiology is very complex, but simply put the fish must work to maintain its blood pH the same as the water it lives in, so the greater the difference between preferred and actual, the more the effect on the fish.

Temperature drives the metabolism, and tropical fish species function best within fairly narrow ranges. Tropical habitat waters generally do not fluctuate very much in temperature, diurnally or seasonally. A couple degrees is not very much, and that is about all the fluctuation there is in waters of South America and SE Asia. The range for a species means that the fish should have no significant issues within that range, but it also generally means the fish will not do very well as either extreme long-term. Mid-range is usually the safe area for long-term maintenance, with the high and low extremes tolerated short-term such as during hot weather and similar. Having said that, fish tend to function best (= with the least effort) in lower rather than higher temperatures within the range. The warmer the water, the harder the metabolism must work just to maintain normal bodily functions, and long-term this can seriously weaken the fish, leading to a weakened immune system, stress, shorter life-pan, and health issues that the fish should normally be able to fight off.

In all of this, something to remember: each and every species of fish will function at its optimum best in the water of its natural habitat for which it has evolved over thousands of years. No exceptions. But obviously there is some adaptability, to varying degrees, among some but not all species, to differing parameters. But this has limits. And while in many cases the fish may be able to live normal lives in such water, it is still a scientific fact that they are guaranteed to function best in the habitat water parameters. So providing water that is as close as we can to what the fish are designed to live in with the least amount of difficulty, will mean healthier fish.

There is much beyond water parameters that affect a fish...every aspect of the environment does. This means the lighting, filter flow, substrate material, decor, numbers of the species, other species...all of these impact fish metabolism, physiology, health, temperament. And each of these governs the rest in a sense.
 
The swordtails are these guys "Xiphophorus hellerii", as I understand there captive breed ones which is where the specified colour/styles come in.
Seriously fish list them as max 8cms max?

This is remarkable complicated, makes me wonder how it's possible to keep them going!!

Does them being captive breed make a difference?
I've seen lots of messages with people keep species well outside they listed parameters and that multi generation captive breed species are quite different to their natural counter parts (this is anecdotal obvs)

I cant even find a site that's lists all the hardness parameters for a species so how do you know them
 

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