Once you build an aquarium go to your marine guide then Rearrange them in alphabetical order. Now when you go to the aquarium and do exchange you can see fish you've never seen before.
Get Unlimited Rebreather
First get titanium alloy by combining Vanadium + Titanium Ore. Now combine Titanium Alloy + rebreather 10 to get Unlimited Rebreather
Item Combos
Acetic Anhydride + Acetyl Acid = Aspirin
Beryl Knife + Basalt = Magnetite/Jade /Augite
Beryl knife + Calcite = Limestone/Marble
Beryl knife + Gabro = Magnetite/Titanium Ore/Apatite
Beryl Knife + Granite = Orthoclase/Quartz
Beryl knife + Opiment = Yellow Paint
Deep Sea Water + Mega-ade 1000 = Mega-ade 2000
Deep Sea Water + Mega-ade 2000 = Mega-ade 4000
Deep Sea Water + Mega-ade 4000 = Mega-ade 8000
Deep Sea Water + Mega-ade 500 = Mega-ade 1000
Deep Sea Water + Tourmaline = Mineral Water
Diamond Knife + Calcedony = Carnelian/Sardonyx/Chrysoprase
Diamond Knife + Corundum = Ruby/Sapphire
Diamond Knife + Quartz = Citrine/Crystal /?
Limestone + Gabro = Cement
Mineral Water + Mega-ade 2000 = Supertonic Turbo
Mineral Water + Mega-ade 4000 = Supertonic Extra
Negative Ion Water + Mega-ade 1000 = Supertonic Dash
Negative Ion Water + Mega-ade 4000 = Royal Ampoule
Negative Ion Water + Mega-ade 500 = Supertonic
Ring + Tourmaline = Ion Ring
Snake Bite + Killer Spider = Scorpions Tail
Titanium Alloy + Rebreather 10 = Infinite Rebreather
Vanadium + Titanium Ore = Titanium Alloy
Water + Mega-ade 300 = Mega-ade 500
Water + Mega-ade 500 = Mega-ade 1000
Water + Oxidized Alcohol = Disinfection Liquid
Water + Tourmaline = Negative Ion Water