Some Tips For Keeping Ornamental Fish in Aquarium.

Keeping freshwater ornamental fish as pets in an aquarium needs some tips to make them live vigorously, healthily, and vividly.
Here are some tips I can share from my own experience :

Fish which are going to live in the same aquarium/tank should be selected based on their types and characters.

Some particular fish belong to sociable fish. They can live together with other fish of the same or different species since the belong to the same level. On the other hand, other type of fish as predator and prefer being kept individually. If we mistakenly mix those different character in the same tank then the tank will become a killing field for the inferior fish.

Sociable fish, they can be kept collectively :

Tetras: Black tetra, black phantom tetra, black widow tetra, cardinal tetra (Paracheirodon axelrodi)

Tiger barb (Barbus tetrazona)

Guppy (Poecilia reticulata)

Panda catfish (Corydoras panda)

Discus (Symphysodon discus).

Predator/Solitary fish:

Flower horn (Amphilophus sp)

Cichlasoma sp (family of Cichlidae)

Arowana (Schleropages formosus)

Although we are talking about fish but learning from an English saying :"Birds of a feather flock together", only fish belong to the same types/character can be kept together.

Water quality plays an essential role in fish life. About 90% of fish survival is determined by water quality which provides sufficient oxygen,  pH (ranging 6.8 - 7.5), no poisonous chemical, etc.

Make sure that water circulation and aeration in the aquarium run well and you can add more oxygen supply to the water using a bubble pump if necessary. I don't use bubble pump for my tank but keep the water circulation and aeration working properly instead to maintain my fish live prosperously.

Well managed water quality enables your fish live much healthier and longer.

Fish need food to live but its availability in water mustn't be excessive since it will make another problem in fish environment.

Fish food contains protein and if fish can't eat up all of it then it will deposit at the bottom of the tank. The deposits sooner or later will create methane gas which is poisonous to fish.

Feed your fish in just enough amount of food. You'll know the amount of food you've given is enough or too much from how long the food stay in the tank. If there is leftover which stays too long (more than 15 minutes) in the tank, it will sink at the bottom and that means you given too much food.

Don't worry about your fish being in short of food as long as you can maintain the water quality ideally. As mentioned above water quality is more important for fish survival than the availability of food. Fish can survive in your tank for one week without supply of food as long as they live in quality water but they 'll die soon if they live in bad water quality with abundant food.

Don't change the food type abruptly since this condition will stress your ornamental fish. Be consistent with one brand of food which your fish has been familiar. Different food brand may contain different composition and this may also cause interference to fish .

If you eventually have to change the food type with other brand since you can't find the same brand anymore, try to mix it with the old type so the fish won't experience a sudden/extreme change in their food consumption. I recommend that you buy some packs of the same brand at one time to anticipate this condition so that you don't have to change the food types too often.

4. Ornamental Plants.

My experience says that only small fish can live with alive ornamental plants but not the big, carnivorous ones. So if you want to grow natural ornamental plants in your tank together with ornamental fish you can consider Tetra (there are some species of this kind), Tiger barb, Guppy and Corydeoras.

You certainly need more equipment to be installed  like CO2 tank, ultraviolet lamp needed by green plants to grow healthily.

If you want fish which are easily bread in your aquarium then Guppy (Poecilia reticulata) should be considered. This small and colorful fish are not only easy to be kept but also fast to breed. What they need to have for their breeding environment are hiding places to keep their eggs and young offspring, number of population (should not be too dense), the absence of predators, and healthy water.