TANK ITSELF:
If you want to go for super cheap and don't want something particularly big you can actually use plastic tote bins as tanks. You can get them as big as 50+ gallons but they do bow quite a bit which can be very nerve-wracking! I used one for my first
betta fish for his first few months, only changed to glass because I found a 5 gallon tank on the side of the road. If you get those heavy-duty black bins from stores like home depot you can fairly easily turn it into a top-view pond-style tank.
For inexpensive glass lids go to your local dollar store and get picture frames that match the width of the tank and take the backing off. If the glass is the right size you can use that alone to lay on top or just
silicone it directly to the frame. Attach little knobs for easy movement and bam- glass lid.
Speaking of silicone! Don't buy that overpriced aquarium sealant from fish stores- just get 100% silicone caulking from the hardware store. The best one in my opinion is GE Silicone 1- its clear, fully silicone, aquarium safe, found in most stores, and is only a couple dollars. If you don't want the big tube you use a gun with it also comes in squeeze tubes. I like to keep a bottle on hand just because I get all my tanks second hand just in case I need to fix a leak- haven't had to yet!
I find sponge filters the best personally and they are fairly cheap to get but there are
diy options! With just an
air pump, tubing, an
airstone,
polyfil, and some sort of pot or cup you can make one yourself that blends in a lot better than a big sponge. It's cheaper if you already have the fluff and pot of course. Another filter diy option is to just get a cheap pump off of amazon and pump the output through a container holding media. This works and looks particularly good in pond style builds because if you're particularly crafty you can hide it behind a little waterfall.
Lights depend on what exactly you want from the tank. If you want to grow plants you may want to get something nice like a
nicrew but you don't necessarily have to. A lot of people in the hobby have had success using shop lights and flood lights for their
planted tanks, even ones that are full of them. If you just want something to light it up enough to see inside just about any lamp will do. A goose-necked one may be a better option just so you can direct the light better.
DECOR:
Kids play
sand is super cheap, you can get like 50lbs for 5 dollars and it looks great! Most stores that sell sand will also sell similarly sized and priced bags of gravel/pebbles if thats more your style.
As everyone else has mentioned collecting things from outside is obviously the cheapest option but it also can take a bit of time preparing things and finding them- lots of fun to go on an adventure for sticks though!
Using hot glue and some
fake plants from the dollar store you can also make some pretty neat decor. This could be a fun craft to do with kids too. I do this myself and actually
made a tutorial on it if you want to give it a try.
While you're at the dollar store take a look at the plant section- they will likely have terracotta pots. They are usually super cheap and add a nice pop of colour in tanks. I really like when they start to grow algae and get that aged look to them. You can break them up for a more natural look, use them as actual planters, or use them as hides. You would likely want to either plug up the hole in the bottom or completely knock the whole thing out though as a lot of fish might get stuck trying to get through it otherwise. Obviously you would want to sand down any sharp edges as well. If you end up using live plants
Java fern will root to it over time too.
If you want actual ornaments like those you find at petsmart you can typically find them for dirt cheap secondhand. People usually are going to just throw them away if they don't sell them.
This one is only cheap if you have or have access to items beforehand or have use for them otherwise but- you can diy a 3d background pretty easily. Use styrofoam as a base, carve it up and stick it together with toothpicks and glue to your liking, then cover it in a few layers of concrete/cement. When you're all done just rinse off the loose bits and silicone it in. This will however raise
pH and hardness at first but if you do heavy
water changes for the first while before adding fish it should be fine.
STOCKING:
This is where you may not want to go the cheap route just because this really is the focal point and the reason for the tank as a whole obviously. But you can usually find people rehoming or selling their fish (most often bettas it seems) in local online classifieds like ohmy, craigslist, kijiji (canadian), etc. It can be a bit of a gamble for community fish as you don't really know 100% that their previous tank was healthy but you can sometimes find some really beautiful ones. With bettas specifically you are also often rescuing them from those awful tiny under 1 gallon tanks which just feels good, especially as you watch them recover.
People also very often will post ads giving away pest snails like
ramshorns for free. You may already have them or may not even like them but ramshorns specifically can come in very pretty blues and pinks. I also just really like snails though.
