Sharing some recent experience:
Keeping Flash overall has been a smooth experience so far. Once he was settled into his tank in our home, his eating has been proper and also he appears friendly and not bothered about anything. Mostly seems like a happy-go-lucky chap.
In order to monitor flash mainly, I have setup an IP Camera at home, running all the time, now it helps me to watch him from anywhere, using my phone. Otherwise when ever we were away from home, we were always anxious about his condition.
Feeding: Mostly eats Market Prawns, with either Hikari or AR G1 pellets inside. Secondly give him Mealworm, found one good source where I get Mealworm in my city and I am also learning now how to breed them. First attempt was failure, currently on second attempt where I have now a group of Beatles surviving and doing their act. Waiting for the next batch of mealworms from them, hopefully. Once in a while, for a change, I give flash Dried Frozen Shrimp, he like it for a change. no live food at all.
2 weeks back I got hold of Super worms, a sample to try out. Unfortunately, I observed flash was getting one of his eyes cloudy (minor like a small line) within 2 days of eating super worms. For Cloudy eye did the following treatment: Firstly did a water test and found all water param in safe limit (Ammonia:0, Nitrite: 0, Nitrate<10 ppm, PH: 7.4). Did an immediate water change of 50% and added Ocean Free Aquarium salt and raised temp to 30 C. Temp was already at 27-29 C most of the time before. Cloudy eye reduced within 2 days. Additionally added Ocean Free Anti Cloudy Eye medicine, for any full and final eradication. It was all clear in 3-4 days.
After a week fed him the remaining super worms, and to my surprise, his other eye got similar cloudy eye within 2 days (thus almost concluding that it was due to the feeding of super worms). Did the same treatment like above and his cloudy eye vanished.
Water and Parameters: Have been constantly checking and maintaining water parameters. So far there hasn't been any instance of water related issues. Have 2 Canister filters running on either side of the 6 feet aquarium and I ensure that if I find anything floating around remove them immediately. It is a Bare bottom Tank and the floor is clean most of the time. In general the default water temp is also in the range of 27-29 C. Having Heater, API water test kit and TDS and temp monitor kit to monitor the water parameters. My water change frequency is weekly, around 40% on average. I do monitor the input water parameters before changing and if within safe range, do the change on week end. On few occasions, I found TDS levels increase on tap water source, then I avoid the change on that day and wait.
Other than flash, I have one 4 feet tank where I have a school of Tinfoil Barbs and a separate Betta tank where I have a blue color Betta. Water change frequency is same for all other fish mates.