Black Neon Tetras Overstocking vs. good school size

Hi,
I would like you to share your opinion.
Currently, I have in my 20 gallon long planted tank
5 * Corydoras trilineatus,
5 * Black neon tetra,
4 * Adult sunburst platy,
3 * Baby sunburst platy,
1 * female betta,
and some snails and neocarditis davidi shrimps.

And water parameters are good, 0 / 0 / 10-20.
It's been 2 months since I set this up and so far everyone including plants look fine except
black neon tetras.
They were originally 6 of them, but 1 just died yesterday.
I don't think it is due to disease, but due to stress the reason why I don't know to be honest.
What I observed is that only 2 of them, both bigger females, are swimming around in free space
while all the others are always hiding in their own spots below plants or behind drift wood.

I suspect that it got worsened since I introduced the female betta to the tank, but I don't see any kind of aggression between any of them.
For instance, it is like, when my Yolie, the female betta, accidentally bumps with one of the platy or cory, they
say 'Oops, excuse me.' and then go their own way.
No nipping, no serious chasing, no aggression is seen
among same species and different species even at meal time
based on my observation.

The black neon tetras are all from the nearby pet store, which means the water parameters such as PH and
hardness are about the same with the current tank.
I confirmed that they use just tap water that is conditioned.

I came to think that I need to do something before all 3 males die from stress.
And one option seems to be increasing the size of school significantly like from 5 to 15, i.e., adding 10 more of them.
And on top of that, I am thinking about adding significant more amount of IAL extract to add dark color.

But then I am worried this will overstock my tank.

Any idea or opinion will be highly appreciated.

Thanks.

 

My thoughts are put the platies elsewhere and bump the neons to 10+. But as an honest note, i tend to be biased against livebearers!

 

I think you should definitely increase the numbers of neons, like add 5-7 more. Not sure if that would overstock your tank though.

When I've added a male betta to a community tank it changed the behavior of a number of fish (they started hiding), even though I didn't see any aggression personally. Two weeks later, two fish were dead. You may have a different experience since every betta is different and yours is a female.

 

My thoughts are put the platies elsewhere and bump the neons to 10+. But as an honest note, i tend to be biased against livebearers!

Could have been my post.
The tank screams "Tetras!" at me, so rehome the platies and get some charact...eeer, characin fish in there.
Edit:

And on top of that, I am thinking about adding significant more amount of IAL extract to add dark color.

Another reason to rehome the platies. Tetras and Bettas love that stuff. But livebearers are hardwater fish, they do not do well in acidic conditions.

 

Another reason to rehome the platies. Tetras and Bettas love that stuff. But livebearers are hardwater fish, they do not do well in acidic conditions.

It's my understanding that adding leaves, wood, etc won't lower the pH much, if at all, in hard water. Is that correct, or have I misunderstood something?

I agree with moving the platys out and getting more black neon tetras, by the way.

 

It's my understanding that adding leaves, wood, etc won't lower the pH much, if at all, in hard water. Is that correct, or have I misunderstood something?

I agree with moving the platys out and getting more black neon tetras, by the way.

No, you're right, but the OP wants to add IAL extract, not botanicals.
Store bought extract can contain stronger acids that artificially lower pH like a pH-down product. Also the OP has soil, which lowers the pH and hardness aswell, so I assume the pH already to be too low for platies.

 

Could have been my post.
The tank screams "Tetras!" at me, so rehome the platies and get some charact...eeer, characin fish in there.
Edit:

Another reason to rehome the platies. Tetras and Bettas love that stuff. But livebearers are hardwater fish, they do not do well in acidic conditions.

No, you're right, but the OP wants to add IAL extract, not botanicals.
Store bought extract can contain stronger acids that artificially lower pH like a pH-down product. Also the OP has soil, which lowers the pH and hardness aswell, so I assume the pH already to be too low for platies.

Thanks for considerate advice. But my IAL extract is not a product, but what I DIY by boiling a IAL, which has not changed PH or hardness at all. Just for the purpose of adding some tannin and dark color.
With no offense in my mind, I rather guess tetra thread writers might not adore livebearers such as platies. Am I right?
But in fact I do love my platies.
Can I do something instead of giving away my platies? How about adding just 5 instead of 10 black neons? Is it still overstocking?

 

Thanks for considerate advice. But my IAL extract is not a product, but what I DIY by boiling a IAL, which has not changed PH or hardness at all. Just for the purpose of adding some tannin and dark color.

I was expecting it, but as of late a few more explicitly Catappa leaf extracts have entered the market, so I couldn't be sure you meant DIY or store-bought.

With no offense in my mind, I rather guess tetra thread writers might not adore livebearers such as platies. Am I right?

With offense to the fish (not the keepers), yes. I'm not against livebearers per se, but they stand for what's going wrong in community tanks, because it's usually their needs that make such a tank hard to manage.

Can I do something instead of giving away my platies?

Get a second tank or rehome one of the species.

To determine which would be more feasable: What are your readings for pH, KH and GH? That could make the decision quite easy and fast. You mention to measure them but don't give numbers at any point.

 

I was expecting it, but as of late a few more explicitly Catappa leaf extracts have entered the market, so I couldn't be sure you meant DIY or store-bought.

With offense to the fish (not the keepers), yes. I'm not against livebearers per se, but they stand for what's going wrong in community tanks, because it's usually their needs that make such a tank hard to manage.

Get a second tank or rehome one of the species.

To determine which would be more feasable: What are your readings for pH, KH and GH? That could make the decision quite easy and fast. You mention to measure them but don't give numbers at any point.

pH is consistently 7.9-8.0 with or without IAL extract. I don’t have any test kit for KH and GH, but based on my location, southern California, I know my tap water has quite high KH and GH.

 

Based on the pH I'd also expect high GH and KH.

Ok, with that water, turn it around: Livebearers it is. Your water is optimal for them.