My Betta is not himself after first water change

[PBower73]

Housing
What size is your tank? 1 Gal
What temperature is your tank? 78 according to the thermometer
Does your tank have a filter? No
Does your tank have an air stone or other type of aeration? No
Is your tank heated? No
What tank mates does your betta fish live with? None

Food
What type of food do you feed your betta fish? Betta Pellets made by Aqua Culture.
How often do you feed your betta fish? Once a day

Maintenance
How often do you perform a water change? Weekly
What percentage of the water do you change when you perform a water change? 100% as instructed
What type of additives do you add to the water when you perform a water change? BettaSafe by Tetra a water Conditioner

Water Parameters:
Have you tested your water? If so, what are the following parameters? No

Ammonia: n/a
Nitrite:n/a
Nitrate:n/a
pH:n/a
Hardness:n/a
Alkalinity: n/a

Symptoms and Treatment
How has your betta fish's appearance changed? Fins have drawn in and seem almost tattered looking.
How has your betta fish's behavior changed? Betta use to swim in the middle and bottom section of tank. He now is swimming very little and is always near the top of the tank. When first placed into the new water he did swim on his side at first and then recovered into the upright position after a few hours. He did begin to swim around like normal and than he displayed the above conditions.
When did you start noticing the symptoms? Directly after changing water.
Have you started treating your fish? If so, how? Yes, We have removed the betta from the tank water and placed into new water that is in the water change bucket. Once placed in the bucket he began to swim around at the edges rapidly however after about 1/2 an hour he settled down and began to hide under one of the leaves of the plant we placed in the bucket to give him some shelter.
Does your fish have any history of being ill? None
How old is your fish (approximately)? we got him as a birthday gift so no idea.

Any help would be appreciated. This is the first time we have owned a Betta and the first time that we have changed the water since placing him in the tank a week ago.

[Oldfishlady]

Often when you see behavior changes after a water change-especially 100% changes. It can be due to either-forgotten or not enough dechlorinator used and/or extreme temp and/or chemistry change or not properly acclimated.

What I would do-make a 50% water change(leaving him in the tank) using like temp water (test using an independent thermometer) along with double dose dechlorinator. Turn off the light and hold food for 24h. Make another 50% with like temp double dose dechlorinator tomorrow. If this is not due to osmotic shock-he should be better in a couple of hours up to 24h, however, if it was osmotic shock or left in untreated water for too long-it can be fatal within 72h.

Keep us posted....

[PBower73]

Oldfishlady,
Thank you so much for your reply. Sadly though Garus, my Betta, did not survive past the day I wrote this. This experience has educated myself and my partner though on Betta care and we are going to follow some of the suggestions about the care and upkeep.

Philip

[Oldfishlady]

Sorry for your loss, stuff happens and I am happy to hear you are not giving up....Look forward to hearing about and seeing your new Betta-