Beginner Supplies

Again, these are either products I use or recommended but it's not things you have to buy. You do what you want to invest it, but these examples are given to help with care towards your fishy friends :D This list is gonna be lengthy since I'm going to explain the importance of each equipment to help you understand why I think you should have them as well as educate a beginner!

[bu]Water Tests
Now, along with the nitrogen cycle, I find water test kit also important. You won't be able to know your tank is cycled without testing. Sure, you could wait however many months and hope for the best, but most problems fish get usually have to relate to the water quality and a keeper can't necessarily say if a tank is okay when they can't read how many nitrates/harmful stuff is in it. With a dog, you can at least see their excrement and pick it up. With fish, their excrement, extra food and other waste is diluted in the water (meaning a naked eye can't see it). Just like picking up after a dog, we should ensure their water/home is in good quality.

API Freshwater Test Kit: https://www.amazon.com/API-FRESHWATER-800-Test-Freshwater-Aquarium/dp/B000255NCI/ref=sr_1_2?keywords=api+water+test+kit&qid=1565144701&s=gateway&sr=8-2
Test Strips: https://www.amazon.com/5-IN-1-AQ-Test-Strips-100CT/dp/B077YS7Y4Y/ref=sr_1_3?keywords=api+water+test+kit&qid=1565144701&s=gateway&sr=8-3

[bu]Heaters
Since bettas are tropical fish, we should provide heaters. Most keepers do not keep their homes heated enough to keep proper and stable temperatures for bettas. They like 78-82F which means you'd need your house temperature around 80F or so as the water temperature will usually be a little lower than the air temperature. I also mentioned stable, and providing a heater ensures the temperatures stay stable. Your house can get warm during the day but cool during the night, and a heater will ensure a fish does not experience too many fluctuations that could cause stress or shock (shock is a term used when a fish experiences too sudden of change in environment, and depending on severity of shock, the fish could become sick or die). With this, I recommend adjustable heaters as most preset heaters only get to 75F which is not hot enough for most bettas. Adjustable heaters would also allow possible treatments (like gradually raising the temperature for ich).

[u]Also, depending on the volume of your tank, it will determine the wattage of your tank. Just let me know what tank you plan on and I can recommend what wattage you should use.

Since heaters are electrical equipment, I personally prefer to invest good money into them. I do not recommend aqueon or tetra products. None of their products have lasted over 3-5 years which resulted in me buying a lot of replacements over my 9 years. In general terms, I am not a fan of glass heaters since when they break, they can crack or even shatter (which has happened three times on me but thankfully I did not lose fish). I love metal/titanium heaters since they won't shatter if they break (but they generally are more durable).

Aquatop: https://www.amazon.com/Aquatop-Aquarium-Submersible-Heater-50-Watt/dp/B006MLVLDQ/ref=sr_1_3?keywords=aquatop+heater&qid=1565145494&s=gateway&sr=8-3
Hygger: https://www.amazon.com/Hygger-Submersible-Adjustable-Heat-Resistant-Controller/dp/B07G4CHQS2/ref=sr_1_2?keywords=hygger+heater&qid=1565145484&s=gateway&sr=8-2
Cobalt (the only one I don't own out of these three): https://www.amazon.com/Cobalt-Aquatics-31021-Mini-Therm-Heater/dp/B0090I7TDO/ref=sr_1_2?keywords=cobalt+heater&qid=1565145467&s=gateway&sr=8-2

[bu]Filters
Again, another electrical piece of equipment so I recommend investing more into these. I do not recommend Aqueon, Tetra or Marineland products in this range as I do not find them good enough quality. Affordable, but none of these filters lasted long enough with me even with proper maintenance.

Beneficial bacteria (which is important for a nitrogen cycle) lives on all surfaces of the tank: decor, plants, substrate, tank walls, etc. However, majority of it is in your filter since this is where the most oxygen/carbon dioxide exchanges occur and beneficial bacteria thrives with oxygen. I find it important that a filter has good capacity to hold plenty of biological media (i.e. lava rock and is the stuff where majority of your bacteria lives) then have some room for customization of mechanical (i.e. filter floss which helps catch debris) and chemical (i.e. activated carbon which helps remove certain toxins (usually needs to be removed for medications)) media. Media in this sense means the type of materials your have in your filtration system. I tend to prioritize biological, mechanical then chemical (and I wouldn't mess with chemical as a beginner unless needed).

Bettas do like soft flow as they come from slow moving and sometimes still waters. An adjustable HOB or sponge filter are what I recommend. A sponge filter would additionally need standard air line tubing and an air pump.

Aquaclear HOB: https://www.amazon.com/Aqua-Clear-Fish-Filter-Gallons/dp/B000260FUM/ref=sr_1_1?keywords=aquaclear+hob&qid=1565146161&s=gateway&sr=8-1
Sponge Filter: https://www.amazon.com/XY-380-Aquarium-Biochemical-Sponge-Filter/dp/B0051XIN78/ref=sr_1_11?keywords=sponge+filter&qid=1565146169&s=gateway&sr=8-11

[bu]Thermometers
Similar to water test kits, we also need these to know what temperature the water is at. It ensures your tank isn't overheating, too cold or other peculiar readings. For example, our AC unit broke in my home earlier in the summer which resulted in one of my tanks reaching 85F (and it's normal temp. is 76F). I was thankful of this since it ensured I needed to work on gradually cooling the tank down so my fish wouldn't get stressed from too hot of temperature. There's all kinds of thermometers, and I haven't really found a brand I particularly dislike. It's more so the types I dislike which these stickers you put on the side of your tank. They don't have a long lifespan and they gunkk up the outside of your tank. The other one I dislike are floating ones since they can get pushed by the water flow, bother the fish and overall be a hassle to catch it to get a reading. My personal favorites are magnet or digital ones, but you go with whichever you think will work best for your set up.

Magnet: https://www.amazon.com/JW-Pet-Smarttemp-Thermometer-Accessory/dp/B002ZMFM4A/ref=sr_1_3?crid=13IZVSJ7XIDQB&keywords=magnet+aquarium+thermometer&qid=1565146657&s=gateway&sprefix=magnet+aquarium+therm%2Caps%2C211&sr=8-3
Digital: https://www.amazon.com/Zacro-Aquarium-Thermometer-Terrarium-Temperature/dp/B01A0TMS6Y/ref=sr_1_4?crid=13IZVSJ7XIDQB&keywords=magnet+aquarium+thermometer&qid=1565146657&s=gateway&sprefix=magnet+aquarium+therm%2Caps%2C211&sr=8-4
Suction Cup: https://www.amazon.com/Marina-Floating-Thermometer-Suction-Cup/dp/B0002AQITK/ref=sr_1_6?keywords=aquarium+thermometer&qid=1565146717&s=gateway&sr=8-6
Hang on side: https://www.amazon.com/Marina-11203-Stainless-Steel-Thermometer/dp/B0002AQIU4/ref=sr_1_33?keywords=aquarium+thermometer&qid=1565146717&s=gateway&sr=8-33
Sinking: https://www.amazon.com/JW-Pet-Standing-Thermometer-Accessory/dp/B003U84S3O/ref=sr_1_3?keywords=aquarium+thermometer+sinking&qid=1565146776&s=gateway&sr=8-3

[bu]Substrate
Now, with bettas being top dwellers, it doesn't really matter what substrate you go with in that sense. However, if you want to do live plants, that can change. I don't want to recommend too many options unless you know which you want to go with. Let me know if you'd like live plants (and what kinds you'd like) and I can suggest different options (depending on what you want to invest in).

[bu]Lights
Lights usually help give our fish sleep cycles as well as provide other nutrients for plants. With this, I again will hold off on recommendations in this subject depending on whether you want live plants or not.

[bu]Siphon/Gravel Vacuum
You could use a cup (designated for fish use) to do water changes, but I find a siphon really makes the process easier (and sometimes more enjoyable). I like manual ones. Electric ones can be finicky and harder to maintain. As long as you get one with a manual pump, it should work. Ensure that you buy appropriately sized siphons as well. I would probably do option 1 for smaller tanks with option 2-3 for larger tanks.

A cheaper option is buying clear plastic tubing from your local hardware store as well, but they usually won't have pumps. These are still easy to use since you put your thumbs over either end and submerge the one end in your tank and make sure the other end in your bucket is lower since we are using gravity in our favor. Release the thumb under the water then the one in the bucket and water should flow. It takes a bit of practice and finding the right height difference between both ends, but this is one way to go cheap.

Option 1: https://www.amazon.com/Jeeco-Aquarium-Controller-Extendable-Changing/dp/B07PL9GZYX/ref=sr_1_7?keywords=aquarium+siphon&qid=1565147122&s=gateway&sr=8-7
Option 2: https://www.amazon.com/Genuine-TERA-PUMP-Aquarium-Controller/dp/B011DDJZ9Y/ref=sr_1_4?keywords=aquarium+siphon&qid=1565147122&s=gateway&sr=8-4
Option 3: https://www.amazon.com/Aqueon-Aquarium-Siphon-Cleaner-10-Inch/dp/B004RK405A/ref=sr_1_5?keywords=aquarium+siphon&qid=1565147122&s=gateway&sr=8-5

[bu]Buckets
Ensure that you have buckets reserved for fish use! These will help with water changes, quarantining and overall are a fishkeeper's best friend :D I re-purpose my kitty litter buckets for fish use (thoroughly rinse them out and dry out for over 24 hours). You can really use any bucket as long as it's sanitized and only for your fish.

[bu]Food
Bettas are carnivores/insectivores. This means their diet should be all meat protein.

I tend to base my fish diets with a staple pellet and variety of other foods (more dry foods, frozen and live food). For bettas, as fry, it is important to provide a lot of protein which can be provided with live foods. With adults, I don't find it a requirement. As long as they are fed good quality and variety, they should be good. A staple pellet should allow them to get majority of nutrients they need where as varieties can be fatty/occasional treats, provide further nutrients or overall a food you wouldn't want as a staple. For now, I'm just going to recommend different pellets. I wouldn't worry about frozen for a while as it's a bit of an investment.

Now, I also in general don't recommend flakes or freeze dried foods as they generally have less nutrients, shorter lifespan and overall fish have a better time with pellets in my experience. Hikari is one of the few brands I know who ensure their freeze dried products are given nutrients back (as freeze drying usually results in the food losing a lot of nutrients). You most likely should replace pellets after 5 or so months were flakes/freeze dried would be replaced every month due to them losing nutrients. That's why I recommend not buying too much for now as a betta does not go through a lot of food. If you'd like a recommendation of a feeding schedule, let me know and I'll explain.

Hikari: https://www.amazon.com/Hikari-Usa-AHK19110-Biogold-0-70-Ounce/dp/B00025Z74C/ref=sr_1_1?keywords=hikari+betta&qid=1565147662&s=gateway&sr=8-1
Fluval Bug Bites: https://www.amazon.com/Fluval-Bites-Betta-Shrimp-Fish/dp/B07BRC35Z9/ref=sr_1_1?keywords=fluval+bug+bite+betta&qid=1565147735&s=gateway&sr=8-1
Omega One: https://www.amazon.com/Omega-Betta-Buffet-Pellets-Food/dp/B01DFT93TG/ref=sr_1_1_sspa?keywords=omega+one+betta&qid=1565147751&s=gateway&sr=8-1-spons&psc=1&smid=A27VFF8Z5BG601
Life Spectrum: https://www.amazon.com/New-Life-Spectrum-Betta-70g/dp/B077MG4JR2/ref=sr_1_1?keywords=life+spectrum+betta&qid=1565147774&s=gateway&sr=8-1

[bu]Lid
Certain fish are more prone to jump than others and this includes bettas. Although, most fish usually jump if stressed. I use lids on and off as the only time I had a fish jump was when the tank wasn't scaped and the fish were very pale/stressed (just brought my fish back home from a cleared flood evac). Although, this doesn't mean I recommend you not have one. It's really up to you if you want to invest in one or not. I use plexiglass scraps from my local hardware store, but you can also use greenhouse roofing or buying glass lids. I don't like hoods as they usually limit your lighting options (which may not matter unless you want live plants).

There may be a few more things, but I think this is a good list to start with. It is a lot, but fish are not cheap pets when you take care of them right. There are ways to go cheap about it (use tubs, low-tech plant tanks, etc.), but of course any animal is going to take some cost to take care of.