My name is XXXXX XXXXX I am a Vet Tech and also have been keeping fish for over 40+ years.
Can you tell me about the tank you have your Betta in?
Have you checked the water Parameters?
Can you tell me the readings for Ammonia, Nitrites and Nitrates?
How much aquarium salt did you use?
Is there any white(salt like spots or cottony areas) or red steaks on the body?
The black spots can be ammonia burns. You may want to pick up an API master test kit to do water tests at least once a week until the tank is established: http://www.amazon.com/API-Freshwater-Master-Test-Kit/dp/B000255NCI. When a new tank is set up, you go through ammonia spikes and this can cause fin ripping: http://www.bestfish.com/breakin.html. I suspect that is what is happening. What I suggest is since you have a one gallon tank only do a partial water change of 25% if the water seems to get cloudy, or every other day. The water needs to remain in the tank with the Betta to stabilize and get a natural bacteria that helps with ammonia, nitrites and nitrates. You can help it along by using Fritzyme #7 which is to help exstablish the tank with nitrifying bacteria: http://www.fritzpet.com/fritz-zyme-7/. You can also use Stress Coat in the tank instead of the Melafix for healing of the fins: http://www.amazon.com/Stress-Coat-Water-Conditioner-16-Ounce/dp/B000255MZG. The Fritzyme #7 and Stress coat will help heal the fins and estabilsh the tank. Do not add any more salt unless the water is completely changed, since it stays in the water. If conditions are correct you should never have to do any more than a 25%- 50% water change once a week. At that time you would add the stress coat to the new water. Please let me know if you have further questions. My goal is to assist you and give you 100% Excellent Service. Joan
A partial water change is done by just taking 25%-50% of the water from the tank and replacing it. You should not have too much waste, since the average feeding is 1-2 pellets twice a day for one Betta. If the bottom is dirty, you can do a 75% change by putting the Betta in a separate bowl and vacuuming the gravel or stirring up the tank and changing the water. By doing a full water change, you are removing the natural bacterial filtering system to keep down the Ammonia, Nitrites and Nitrates. That is why I suggest using a test kit. You do not need to do a full water change for the melafix and the Fritzyme#7(use when starting the tank and in water changes) and Stress coat (every few days) are sold in most Pet shops. I have two Bettas right now in Betta bowls and only do the partial water changes, with no problems. I have a crown tail and a normal. Joan
You do not need to remove Gil for partial water changes. The Test kit has a chart and complete instructions, The Ammonia should be 0, Nitrites 0, Nitrates 20ppm or less and PH 7. The Fritzyme conditions the water and adds nitrifying bacteria to help the tank start faster. Once the tank is extablshed (usually 30 days) you can stop the Fritzyme and just use a anti chlorine drops. The Stress Coat is for healing and once healed, I suggest once a week, to protect his fins. If you are testing the water and the parameters are normal there is no need for a water change, unless the get higher than normal or very cloudy. The normal water changes will be 25%-50% when the water is cloudy or dirty. I rarely do a total water change because once the tank is established, you should not have to do full changes, just enough to keep the water clear.
On a side note: You can get a small in tank filter for the one gallon tank if you cannot keep it clear. Tetra makes a small filter that goes right inside the tank and is great to save on water changes. Joan
Thanks so much for your help!