Hi Tyler and welcome to the forum
I like the watermelon with the heart glasses. That's great. I wouldn't have it in a tank but it's a funny piece that would go well on the shelf.
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Any idea what the GH (general hardness), KH (carbonate hardness) and pH of your water supply is?
This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).
I ask because you have an assortment of fish that come form hard water and soft water living together in the same tank. I would look at moving them around so the soft water fishes can live together in soft water, and the hard water fishes can be kept in a different tank with hard water.
Depending on what the GH of your water is, will determine what fish you should keep.
Angelfish, most tetras, barbs, Bettas, gouramis, rasbora, Corydoras and small species of suckermouth catfish all occur in soft water (GH below 150ppm) and a pH below 7.0.
Livebearers (guppies, platies, swordtails, mollies), rainbowfish and goldfish occur in medium hard water with a GH around 200-250ppm and a pH above 7.0.
If you have very hard water (GH above 300ppm) then look at African Rift Lake cichlids, or use distilled or reverse osmosis water to reduce the GH and keep fishes from softer water.
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You have hatchetfish with rainbowfish and Buenos Aires tetras. This is a bad combination where the hatchetfish will probably starve.
Your silver shark looks skinny and would prefer to be in a group of 6 or more. However, they can reach 10-12 inches in length and need a huge tank when mature.
Danios, tetras and rainbowfish all do best in groups of at least 6 (preferably 10 or more) of their own kind.
Black or white widow/ skirt tetras and Beunos Aires tetras are fin nippers that should not be mixed with slow moving fish or fish with long fins.
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You could add some live plants. Water Sprite (Ceratopteris thalictroides/ cornuta) is a floating plant that grows rapidly and can also be planted in the gravel. The floating plants would provide some shelter for the hatchetfish and other tetras, and help bring out their colours more. The white sand and no surface cover is making them fade a bit.
You could add some Duckweed to the tanks and let the rainbowfish eat it. Rainbows need at least half of their diet to consist of plant matter and Duckweed is a great food for them. It is a small floating plant that most people hate but most rainbowfish love it. You can grow it in the other tanks or outside in a pond, and simply add some to the rainbowfish tank when they run out.
