While goldfish and fiddler crabs are both relatively peaceful, they can’t live together as they have different environmental needs. Goldfish are coldwater fish. Since fiddler crabs come from brackish environments, they need roughly 1 tablespoon of aquarium salt added to each gallon of their water.

Hermit crabs require both freshwater and saltwater water sources to survive. You may also choose to use bottled spring water instead of water from your tap to avoid chlorine exposure. The water dishes should be big enough for your hermit crabs to submerge themselves in, but not so deep that they can drown.

Unfortunately, crabs can’t live with goldfish—much of the reason being their different tank requirements. Goldfish like cooler temperatures for one, while crabs like their waters nearly ten degrees centigrade warmer, among other things.

With these ground rules in mind, here are our top 10 tank mates that we have personally tested and found to be compatible with goldfish:

• Hillstream Loach.
• Brochis multiradiatus.
• Dojo Loach.
• Bristlenose Pleco.
• Rubbernose Pleco.
• White Cloud Mountain Minnows.
• Ricefish.
• Hoplo Catfish.

Goldfish by nature are not aggressive, and are not predatory. The short answer would be, “No, they don’t eat each other”. Goldfish tend to browse for food, eating mostly what are bite-sized morsels, of anything edible. …

Do tetras get along with goldfish? Yes, tetras may get along with goldfish, just as they would with some other fish species, but the goldfish can make the water too dirty for them, and big goldfish eat tetras up too.

No, neon tetras cannot live alone in a small fish tank. This tetra gets depressed, stressed, and eventually dies when kept alone in a small tank as neon tetra is schooling fish and needs space to swim. These tetras need ideal parameters to survive and a small tank can barely hold a candle to it.

Equipment: Neon tetras and cardinal tetras are tropical fish and require a heater that keeps the aquarium at about 72–80 degrees Fahrenheit. In addition, they need a filter to provide a home for beneficial bacteria and to aerate and clean the water.

Female goldfish usually have fat, round little bellies, full of eggs. Males show two distinct physical characteristics: 1) Roughened pectoral fins 2) raised bumps on their operculum (see picture below). This is most common in comet goldfish.

Stocking Your 10-Gallon Tank There are some fish advisors who use the ‘rule of thumb,’ which suggests one inch of fish per gallon of water.

Will Koi Eat Fancy Goldfish? Answer: Yes, low risk (small species). While standard common goldfish are usually alright to keep with koi, fancy goldfish, particularly the smaller varieties, should not be kept with koi.

So, your koi carp cannot bite you, and you are perfectly safe to hand-feed your fish without the risk of losing a finger! That said, the mouth and gums of the koi are actually fairly strong and muscular, and they might grasp onto your finger with their mouths, mistaking it for food.