more of the same or different fish?

  • #1
HI there, this is my first post

I've been keeping fish for about 4-5 weeks now and so far so good. no dead fish, although recently I have had quite a high nitrite reading, of which I am taking care of by doing water changes every 2-3 days. I should be testing it tomorrow to make sure its ok now. Anyway, I have a 20 galleon tank which is well planted, has several hiding places and I currently have 4 serpae tetras, 5 neon tetras, 4 corys and 3 amano plant shrimps.

I'm thinking of adding more fish soon and was wondering whether it would be nicer to have 5 more neon tetras or to go with something different, such as harlequin rasboras or glowlight tetras. I've read on sites that having larger shoals brings out their colour more. what would experienced keepers do?
  • #2
First, welcome to the forum

I think having more of the same is more beautiful You're quite right. Shoaling fish feel safer in larger numbers, and when they feel safe they display their best colors as well their most interesting behaviors. Many shoaling fish swim as if they were one - having their bodies positioned in the same direction and making the same moves. It looks stunning from a distance. I don't know about serpae tetras but my guess would be that they're shoaling, so at least 6 of them would be nice (if they don't grow too large - don't know their adult size). Neon tetras are shoaling, and - likewise - at least 6 would be good. If serpae tetras are around the size of the neons, you could add to your tank 2 more serpae tetras and 1 neon, so that both groups are comprised of 6 fish. You could have even more of them, but considering the size of your tank, you don't want to overstock.

If you have a high nitrite reading, you should be performing daily water changes (I'd perform daily 50% or even larger water changes if I had nitrite in my tank). Remember that even smallest amounts of ammonia and nitrite can easily kill your fish, or make them very sick. I assume your ammonia = 0? Do you know your nitrate reading?

Few other questions: How soon after you set up your tank did you add the fish to it? How many fish at once did you add?
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  • #3
Thank you for your advice. I'm not really too sure what my readings are as my LFS is the one that does the tests (as they do them for free) but last time they showed me and Ammonia was trace, Nitrate was in the high end of the spectrum ( quite red) and nitrate was normal around 5-10 I suppose. Since then I've been doing water changes every 2-3 days.

I actually added fish after about 3 days but I used a bacteria supplement, the Tetra one (I can't remember the product name as Ive finished it and thrown away the bottle now). I added some fish food when the tank was still empty and the LFS tested the water for me everyday, and I could see it cycling, but in much smaller quantities. I added 4 serpae tetra and just kept them for about 2 weeks.

After that I got another test done and all was fine, just a bit of nitrate so I did a water change and the next day got 5 neon tetras and 3 plant shrimps.

The next week I got 4 corys and I think that's where I went a bit wrong on the feeding as I over fed the tank with flake and sinking wafers, worrying that the corys didnt get enough to eat (I've figured out how much to give them now) so I guess that's where the nitrite came from.

Its now been about 2 weeks since I added fish but about 1 week since I started feeding correct amounts so I will probably get 5 more neons in the next week or so. Serpae tetra's are a bit bigger than neons, they are about the same size as black widow tetras with slightly shorter finnage.
At the moment, my neons are acting very much separately from each other as they all have their own favourite spots so hopefully with a few more, they will shoal. I will probably stick with just 4 serpae's but they seem to get along fine. they go their own ways as well as shoal so I think they're happy
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  • #4
got another test done today, everything is good but didnt manage to get the readings as the LFS threw away the results before I got back to them ( I went to another shop during that time)

The LFS allowed me to purchase 5 more neon tetras. good thing about them is they strongly advise that they test the water before you purchase fish
  • #5
With the fish list you currently have - 10 Neon Tetras, 4 Serpae Tetras, 4 JuliI Corydoras, and 3 Amano Plant Shrimp - do not add anymore fish to the 20 gallon tank. This is enough. Remember: you don't want to overstock.

If you still have ANY ammonia and/or nitrite readings (no matter how small the readings are), I recommend performing daily 50% water changes, until ammonia and nitrite both = 0. Nitrate should be kept in check after the tank is cycled by regular weekly water changes, say, of 25-50%. Nitrate should also be at 0 (at best) or as low as possible.

I'd also recommend for you to get a test kit (that includes pH, ammonia, nitrite, and nitrate). Aquarium Pharmaceuticals Master Test Kit on Big Al's Online is very cheap. It is also a very good and reliable test kit. It's best to have your own test kit, believe me - you'll need it many times. Here is a link to the test kit on Big Al's:

You'd pay much more for the same test kit at your fish store, or if you bought tests for pH, ammonia, etc ... separately.
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  • #6
Thanks for everyone's advice. As you have mentioned, I do not plan to add any more fish now as I also believe it is full. I perhaps planned to add 3 more plant shrimps as I have heard they add very little bioload and help with cleaning the tank and eating uneaten food but I don't think I'd add them for at least a month.

I don't think I can purchase the test kit from bigAl's as I actually live in the UK. I will have a look around uk sites though for cheap test kits. If anybody has some recoomended sites, please you could you give the link?

  • #7
Here's what I found just doing a google search. I know nothing about these places or their credibility: This place does not have the master test kit, but sells the tests separately and they look quite pricey this way! You might want to email them and see if they could order you a master test kit and give you a price.

This site does carry the master test kit recommended by Isabella

This site carries it also.

They have it also.

You can also try your local shop and ask if they will order it for you.
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  • #8
I'm actually having a problem with the 5 neons I bought 2 days ago.

When I first released them into the tank (after acclimatising temp and pH) the Serpae tetra's immediately chased them as if they were food ( my initial batch of neons are adult size where the new batch are rather small) and unfortunately several have been nipped since. I have read that serpae tetra's are prone to fin nipping but have been reassured by my LFS and some sites that they only nip their own kind and rarely other species, yet one of my neons has lost its tail fin, one has lost its bottom half and one has a visible "hole" in the bottom half. :'( The one with no tail has in fact gone missing now and I have not seen it for at least 24 hours.

was it wrong to introduce smaller neons to my tank? should I take them back and buy some adult ones? (LFS only had small neons at the time, still unsure if they have adult neons now)

Would it be better to replace my serpae tetras and get something more peaceful such as harelquin rasboras or glowlight tetras?

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