How many fish can I have?

Question

I have a 80 litre tank and already have 9 neon tetra, 1 male and 1 female dwarf gourami and 2 mollies. Can I hadd any more fish? I would like a fighting fish and another small shoal of about 6.
I test the water every week and change approx 20 percent every 10 days.

Answer 1

"In case you haven't heard, there is this stupid "rule of thumb" in the aquarium hobby that you can keep 1 cm of fish for every 2 liters of water. Let me start by explaining why that rule should be ignored completely.

Consider a 3 cm Neon Tetra and a 3 cm Goldfish. In terms of waste produced and body mass, it will take about 20 Neons to equal that 1 Goldfish. Also consider a 3 cm Pink Kissing Gourami. The Pink Kisser is just a baby while the Neon is an adult already. That Kisser has a much higher metabolism and therefore will eat more and produce more waste. Also, the Kisser has much more body mass than a Neon. The cm/liter (in./gal.) rule is meant to apply to small fish at their adult size, such as Neons, Cherry Barbs, Cardinal Tetras, White Clouds, and Zebra Danios. Do NOT use this rule for any fish which is bigger than a Neon. Not even for a Platy or a Swordtail.

Now that you can see what I'm talking about, let me explain how many fish you can comfortably fit into your tank. The most important consideration is that you are doing regular water changes and have the appropriate biological filter for your tank size. Provided you are doing the appropriate maintenance and have the correct sized filter, then you will probably never have problems with water quality, regardless of how many fish you put in the tank.

The important considerations are aggression and swimming space. You should never put a fast swimming schooling fish in an aquarium smaller than 200 liters. Many hobbyists assume that they are losing fish mysteriously because the tank is "overcrowded." In reality they are just not giving the fish the appropriate swimming space. When packed into a small tank, "fin nippers" will become very territorial and create stress on your other fish. This is what is resulting in the mysterious fish loss. And it is not related to water quality.

OK, so how many fish? To be honest, there is not a limit. As long as you are putting the fish in the appropriate size aquarium, you will be content with the fish load long before you have reached the biological limits of the tank. I have kept 40 liter aquariums with 30 fish and 200 liter aquariums with 100 fish. The catch is to provide the correct maintenance and be smart about what fish you mix together. Just watch your tank. When your tank starts to look crowded then stop adding fish. There really is no "rule of thumb" for adding fish. This depends entirely on the mix of fish you choose. Good luck! "

Answer 2

don't get a fighting fish aka betta. the gouramis will NOT approve. i've seen bettas get torn apart by gouramis in pet stores. they're distant relatives with similar aggression issues and won't see eye to eye. i'm nursing back to health a poor crowntail who had his fins ripped off down to small stumps by paradise fish (a type of gourami). he's making a good recovery.

your tank is about 21 US gallons, for those who don't work in litres. another school would be pushing it with your neon tetras group already quite large. you may be able to squeeze in a small group of khuli loaches though, what is your substrate? they like fine gravel or sand, and they're light on the bioload, all your fish are mid-top level, so something like khulis down below may work. a group of 3-4 maybe. but you would be pushing your stocking level and need to keep a close eye on those parameters.

all your fish apply to the inch-per-gallon rule, neons at 1"-1.5", gouramis at 2", and mollies can get anything from 3"-6". do the math on those and you're overstocked.

Answer 3

im not sure how many gallons 80 liter is but i think since they that small you can have a few more you are doing great just remember to take the water from the bottom of the tank with a hose i raise fresh water and salt water fish and believe me salt water it a job untill you get your water in good shape fresh water fish is for every inch of fish 1 gallon of water hope this was help

Answer 4

I wouldn't recommend adding another school, but the betta is ok. The tank is very crowded as is. Mollies grow to 6", so consider replacing them with something smaller.

Answer 5

each and every person will in all probability say "blue" fish, yet i'm quirky and could say new fish, or pink fish smoked fish,or pink fish cooked fish, final yet no longer least pink fish stunk like fish!

Answer 6

Yes that would be fine. I own many fish my self as I have a large reef aqaurium. You can get the fighting fish and the small shoal without a problem!!!!

Answer 7

General rule of thumb we used when I worked in the petshop was this:

Length of tank * Width = Water surface area / 40 cm (standard) Now, divide the size, or the average, of the fish you want to add.

Example:
90(cm)* 35 (cm) = 3150(cm2) / 40 = 79 / 5(cm) = 15 fish.

Answer 8

You can have about 40 fish in total, if they are the size of tetras, or about 20 if they are bigger.