Sick Betta?

[Ammolite]

I have two male betta fish in one 30L tank, divided by thick mesh, Ammolite (an unknown breed) and Trellimar (A huge royal blue half-moon) They cannot see each other at all, just to give some basic information as the sickness hasn't come from stress from each other.
 
Trellimar for the past two days has become very lethargic, which is odd for him, as although he is lazy and likes to sit on leaves and sleep, he hasn't been moving almost at all recently, only moving when being fed. He used to be more active, coming up tot he glass and dancing and blowing bubbles for food (which i don't give him unless its meal time, no treats in this house) he used to blow bubbles repeatedly at me and build nests all the time. 
Ammo on the other hand since Trellimar has become this way, hasn't changed in the slightest, he must be the most active betta i've seen. He constantly swims up to the glass and parades himself around for attention and the hope of more food. 
 
I feed them both a mix of Hikari betta bio-gold and Hikari tropical micro pellets, regulating them as they get bored of one food too often (spoilt boys). I also feed them the occasional dried bloodworm (King Britain Bloodworm treats) but only a small pinch, only twice-three times a week. 
 
Trellimar has also been pooping odly, this has not occurred in Ammolite yet but if it does i know it could be a parasite. Some, not all for what I've seen, but some of his poop is long, thin and string like and won't detach itself from Trell. I don't know what this means, or if i have possibly overfed him (Although Ammolite is fine, even being smaller then Trell) 
 
Trellimar also has slight fin rot and for the past 2 days has had some red tips to his fins, he's been suffering from fin rot ever since i got him and nothing i seem to do helps to cure it. Any advice on this behalf too? Ammolite is fine (he's missing half his tail from an accident in the pet store but its slowly growing back) 
 
I was just wondering if anyone had any ideas what the issue could be, I'm going to get the water tested today at my local store, and doing a 50% water change tonight and adding salt (as i always do) 
 
I can attach photos of the two if needed  

 

[NickAu]

 
adding salt (as i always do)

IMO salt is not needed, How much salt atr you adding?
 

 
I feed them both a mix of Hikari betta bio-gold and Hikari tropical micro pellets

I think this food is not the best option, Best options are Atisons betta food or pro, New life spectrum, or Omega.
 
Can you please answer the following questions, It will enable us to give some advice.
 
Housing:
How many gallons is your tank?
Does it have a filter?
Does it have a heater?
What temperature is your tank?
Does your tank have an air stone or other type of aeration?
Does your Betta have tank mates? What kind?
 
Maintenance:
Before your Betta became ill how often did you perform a water change?
What percentage of water did you change?
Do you vacuum the substrate or just dip out water?
What additives do you use?
 
Water Parameters:
What are your water parameters? Please give exact numbers. If tested by pet store please get exact numbers. "Fine" or "Safe" won't help us help you.

Ammonia:
Nitrite:
Nitrate:
pH:
Hardness (GH):
Alkalinity (KH):
 
Symptoms and Treatment:
When did you first notice the symptoms?
How has your Betta’s appearance changed?
How has your Betta’s behavior changed?
Is your Betta still eating?
Have you started treating your Betta? If so, how?
Does your Betta have any history of being ill?
How long have you owned your Betta? Was he or she ill or suffering some sort of damage when purchased?

PLEASE PROVIDE CLEAR PHOTOS

 

[Ammolite]

Firstly, thank you so much for your reply~
 
For the salt i only add in two tea spoons (that treats only 1/4 of the tank) as i was recommended to use the salt but i don't like using too much~ As for the food thank you! I will be buying those brands later on this evening to see if they help perk him up even in the slightest. (Ammo won't mind the food change either as he seems to gobble down everything) 
Id like to note they're only in this tank as i have a 10 Gallon being set up for them currently (Its a natural tank with all real plants and wood, we are also moving house so its taking me longer to set the tank up, so the current tank is only temporary)

How many gallons is your tank;
Apologises there i shouldve written both, its about a 7 gallon i believe when you convert it over
 
Does it have a filter?
Yes and this is regally cleaned and changed when needed with water changes

Does it have a heater?
Yes, a very good one at that!

What temperature is your tank?
At a constant 80 fahrenheit

Does your tank have an air stone or other type of aeration?
I have plants in my tank for hiding places and aeration 

Does your Betta have tank mates? What kind?
1 Corydoras and 2 Otocinclus on the other side with Ammolite there are 3 Phantom Tetras (Who where my sisters given as a present)

Before your Betta became ill how often did you perform a water change?
Once every 5 days to a week
What percentage of water did you change?
30-50% changes depending on the water quality at the time
Do you vacuum the substrate or just dip out water?
Vacum 
What additives do you use?
By additives if you mean water conditioner and products like that i use a regular tape safe along with Nutrafin betta conditioner~ 
 
Ammonia: unknown as my kit doesn't test for this, but I'm heading to my local store today with a sample of the water to see 
Nitrite: 1
Nitrate: 50
pH: 8.0
Hardness (GH): 16
Alkalinity (KH): 15 (Oh geez this needs lowering!) 
 
 
When did you first notice the symptoms?
Now three days ago, the poo has only been happening for two of the days though

How has your Betta’s appearance changed?
Not at all, colours are still the same, scales aren't different in anyway, he was already suffering from fin rot so apart from new red tips to his fins no changes
How has your Betta’s behavior changed?
Before he's swim up to the glass to greet me, chase the cory around sometimes and poke at the Otos, but now he just sits on top of his tower on on the plants for hours on end. TODAY he does seem a little better, he greeted me at the glass, didn't dance for me but still, and he's swimming around a lot more now in comparison to yesterday where he seemed lifeless.
Is your Betta still eating?
Not so much like a pig but he eats all his food
Have you started treating your Betta? If so, how?
​Ive only ever treated him for fin rot, with regular fin rot medication, but it has never helped in the slightest for him 
Does your Betta have any history of being ill?
Fin rot since being brought, he used to go a few days without eating and seem like he's 'sulking' but this hasn't happened in months, he also does have spells of just resting on the tower near the surface of the water a lot, not even just to breathe (as he's not gasping at the air) but just to lay there, he'd do this for a whole day then be active the next, etc etc. But again this hasn't happened in months. 
How long have you owned your Betta? Was he or she ill or suffering some sort of damage when purchased?
I knew before i purchased him that he had fin rot (as did ALL the fish at my local store) but i knew he had also been in a fight with another male that had jumped into his tank, Trell had come out with only one rip to his tail where as the other betta was beaten up (he was a standard compared to Trell who is a massive butterfly half-moon) I've owned him since April of this year (birthday present) 
 
 
​I apologise about the picture quality but these where the best i could get with the 'poo' hanging out of him, you can tell how bad his fins are as half moons have white tips and Trell, well he doesn't.
 

 

 

[Ammolite]

Also, as seen in the pics my tank does have cyanobacteria in it, to which i still haven't managed to get rid of completely

 

[Ammolite]

UPDATE:

He has not eaten anything and his scales are now risen so they're 'pinecone' like, the other betta/fish are still unaffected... He's resting on the bottom of the tank more now then the top, i feel like I'm loosing him. 
I've got anti-stress in there now too to try and help. 
 
No ammonia in the tank either.

 

[NickAu]

You have some serious stuff going on in the tank. IMO none of those fish are suitable with a PH of 8. I also think your tank is over stocked.
 

 
1 Corydoras

Corys should be kept in groups of 6 or more.
 

 
2 Otocinclus

Ottos should be kept in 3 or more 5 is better.
 

 
3 Phantom Tetras

Tetras should be kept in groups of 6 or more.
 

 
Ammonia: unknown as my kit doesn't test for this, but I'm heading to my local store today with a sample of the water to see 
Nitrite: 1
Nitrate: 50

Both these are a problem, Ammonia and Nitrite should be zero and Nitrate should be as close to zero as you can get it.
 
The only way to do this is with water changes.
 

 
Before your Betta became ill how often did you perform a water change?
Once every 5 days to a week
What percentage of water did you change?
30-50% changes depending on the water quality at the time

I think you need to do 50% 2 times a week.
 
Now onto the bad news.
Stop using Aquarium salt, Do 2 or 3 50% water changes every day to get rid of it.
You say you fish is bloated and pine coning? Epsom salt dips and or antibiotics may help but sadly I don't hold much hope for him.

 

[Ammolite]

Trellimar is currently in a hospital tank (with heater) and being treated for suspected dropsy, as he now has most of the symptoms of it :c
 
I used to have both more cory's and ottos' but they all died and these are the ones who remain (i refuse to get more until i upgrade my tank size currently) Also the tetra's my sister got advised only to get 3, so got the three :\ Never buying from my local again i can tell you that. (they also recommended i get other fish which even i knew would over populate my tank, although the tank i have now is only temporary) 
 
There is no Amonia and the Nitrite is now down to 1, doing another water change today and adding anti-stress to the main aquarium to bring this down, i will also do everything you've suggested so thank you, i hope the main aquarium thrives more after all this treatment.
 
As for Trellimar he is almost completely immobile on the surface of the tank, he hasn't moved all night, I'm changing his hospital tank water daily to see if this helps, i hope he pulls through, he was my first betta after all <3 But thank you for all your help. 
 

 

[NickAu]

Good luck hope Trellimar pulls through.