Is a 1-foot marine tank big enough for fish? What can I put in it?

Thanks for reaching out, the rule of thumb is 1" of fish per 3 gallons, but smaller tanks are very difficult to keep stable, and saltwater fish are easily stressed by environmental fluctuations (salinity, temperature, dissolved oxygen). Good luck.

Without anything to use for scale, it is hard for me to tell how big your tank is, but in general it seems very small. Also, the water that is in the tank appears very cloudy right now, so that would be the first place to start. Water quality is very important, and will make or break your ability to house and care for fish. I would recommend getting a good filter system (you can visit a local pet store to assist you with brands in your area, as I am not familiar with what you can get in India). Be sure to bring the measurements (height, length, width) of your tank, or the gallons or liters so they can tell you what capacity of filter you will need. Everything else will depend on what types of fish you get - if you plan on getting multiple fish, they will need to be small - a general rule of thumb is one square inch of fish per gallon of water. Depending on the species you get, you may need to also get a bubbler to ensure there is enough oxygen in the water for them, and you will also likely need to get some sort of substrate for the bottom and cage furniture (different species have different air requirements, and some are secretive and like to hide). You may also need a water heater, depending on the species you would like to house. But, depending on how small your tank is, it may be hard to get a water heater that will fit. The food type will also depend on what species you get, as there can be differences in diet type between species. I hope that gives you a place to start, and good luck!

Yes it is possible, however, unless you have a lot of experience keeping saltwater fish, please do not even attempt it. Most wild caught saltwater fish will not feed when they are in an aquarium, and only a small percentage will ever learn to feed. Please leave them where they are happy and healthy and where they belong, the sea.

The Tang, Clownfish, and Chromis are marine fish requiring a saltwater aquarium while guppies are freshwater fish. These fish are not compatible as they require two completely different setups to accommodate their different environmental needs. If you are going to set up a marine aquarium - a 20 gallon aquarium is too small for the fish you have listed. A small Percula Clownfish maybe suitable in a 20 gallon aquarium temporarily, but be prepared to upgrade to a larger aquarium as it grows larger. In general, 50+ gallon aquariums are recommended to properly house marine fish as they tend to grow large and require plenty of room to swim. If you are planning to set up a freshwater aquarium, a 20 gallon setup is adequate to house guppies.

Before you buy any fish, you will need to set up the tank. A basic set up includes: a tank, filter, hood/light, heater, gravel and some decor. The tank should run without fish for at least 4 to 6 weeks. This gives it time to cycle. The Nitrogen Cycle is critical to the health of the tank and any fish you will be keeping. During this time, beneficial bacterial will populate the filter and substrate (gravel). These bacteria will be responsible for breaking down fish wastes and other wastes (uneaten food, dead plants, etc.). You will need a home test kit to monitor water chemistry (ammonia, nitrites, nitrates, pH) or you will have to submit water samples for testing. Most pet stores will do this for free or for a small fee. At first, you will see high levels of ammonia and nitrites. Over time, as bacteria grow, these levels will drop. When ammonia and nitrites are at 0 ppm and nitrates are below 20 ppm, you can consider adding fish. Regular (every 1 or 2 weeks) partial water changes as well as filter changes will be needed to maintain stable water chemistry and adequate water quality. The size of your tank will determine what fish and how many you will be able to keep. Most Tetras do best in groups, so a 12 inch tank may not be large enough. There are several article in the Petco Pet Education Center, formerly Petcoach Library that will provide more detailed information. Click on "Educational Center" at the top of the page, then scroll down to "Articles" and click. Use the Search Bar to find articles regarding aquarium set up and fish keeping.

Salt water aquarium requires a great deal of regular maintenance to keep the fish alive. This can be helped by adding live rock (similar to live coral) to the aquarium. Below is a link to some great information for maintaining a salt water. aquarium.http://www.madhattersreef.com/20-ways-improve-aquarium-husbandry/ I hope that helps and all is well with your fish.

Guppies or Neons are excellent "starter" fish. Care is simple and they are inexpensive. A standard 10 gallon tank is recommended to start. Most people don' t realize the amount of "work" needed to maintain a tank. Filter maintenance, monitoring water chemistry, water changes, monitoring fish health and providing a balanced diet are just a few items that need regular attention to keep a tank thriving. Even though fish aren't as cuddly as cats and dogs, they do have their own personalities and even respond to their owners, especially at feeding time! Studies have shown that simply watching fish in a tank can lead to a reduction in both heart rate and blood pressure. It is quite relaxing.